monash-ecb1101-microeconomics
May 26, 2026
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我拿到了一份我在上的课的考前宝典！你帮我拆解一下这节课，告诉我复习重点，我快final了
越详细越好，公式，定义，核心考点我都需要，救救孩子
- 下面我就按你这份 ECB1101（Introductory Microeconomics）考前宝典 的思路，帮你把整门课“拆开—串起来—变成拿分动作”。我会把：
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0）先把考试“打赢”：结构、分值、节奏（这决定你复习优先级）
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考试蓝图（你必须背熟）
- Final exam 占 50%；100 marks；2h10m（130 min）；闭卷；覆盖 Weeks 1–11。[1]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdf你已经上过讲座和习题课。凭记 忆重画每张图,再遮住答案做练 习库。“考试招式”框展示了批改 者奖励的步骤。 C 3 . EXAM 3· 考试(EXAM) It's SWOTVAC. The one-line recap and glossary are your map. The blueprint overleaf shows where the marks sit - and why Section C (graphs) decides your grade. 到了SWOTVAC(考前复习周)。 那一行回顾和词汇表就是你的地 图。背面的蓝图展示分值落在哪 里 -- 以及为何 C 部分(图)决定 你的成绩。 i How this book was built 本书是如何编成的 Every model, diagram and worked number here is grounded in this unit's own materials: the weekly problem sets, workshops, online quizzes and the exam information guide (Mankiw is the set text, so the concepts line up chapter- for-chapter). Practice problems are AskSia-authored in the unit's style. Verify against your own Moodle before the exam - details shift between cohorts. 这里的每个模型、每张图和每个例题数字都扎根于本课程自己的材料:每周习题集、习题课、在线测验和考试信息指南 (Mankiw 是指定教材,所以概念逐章对应)。练习题由 AskSia 按本课程风格编写。考前请对照你自己的 Moodle 核实 -- 不同届之间细节会变。 - AskSia Library . ECB1101 · 双语 Bilingual THE BLUEPRINT - THE EXAM BLUEPRINT EXAM . 50% OF GRADE Where every mark lives 每一分都有出处 Half your grade, three sections, and 40 marks of graphs you draw by hand 占一半成绩、三个部分、40分手绘图 IN ONE LINE The final exam is 50% of your unit mark: 100 marks, 2 hours 10 minutes, closed book, covering Weeks 1-11. There is no hurdle - but half your grade, and the biggest block of marks (Section C, 40 marks of hand-drawn graphs), ride on it. 期末考试(final exam)占你课程成绩的 50%:100分,2 小时10分钟,闭卷,覆盖第1-11周。没有及格门槛(hurdle) -- 但你一半的成绩,以及分值最大的一块(C 部分,40分手绘图),都押在它上面。 50% FINAL EXAM 期末考试 100 marks TOTAL PAPER 整卷 2h10m CLOSED BOOK 闭卷 3 sections MCQ . SHORT . GRAPH 选择 · 简答 · 画图 The three exam sections 三个考试部分 Section What Marks A 30 multiple-choice questions 30 B 4 short-answer / calculation 30
- 三部分：
- Section A：30 MCQ（30 分）（定义 + 一步计算）[1]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdf你已经上过讲座和习题课。凭记 忆重画每张图,再遮住答案做练 习库。“考试招式”框展示了批改 者奖励的步骤。 C 3 . EXAM 3· 考试(EXAM) It's SWOTVAC. The one-line recap and glossary are your map. The blueprint overleaf shows where the marks sit - and why Section C (graphs) decides your grade. 到了SWOTVAC(考前复习周)。 那一行回顾和词汇表就是你的地 图。背面的蓝图展示分值落在哪 里 -- 以及为何 C 部分(图)决定 你的成绩。 i How this book was built 本书是如何编成的 Every model, diagram and worked number here is grounded in this unit's own materials: the weekly problem sets, workshops, online quizzes and the exam information guide (Mankiw is the set text, so the concepts line up chapter- for-chapter). Practice problems are AskSia-authored in the unit's style. Verify against your own Moodle before the exam - details shift between cohorts. 这里的每个模型、每张图和每个例题数字都扎根于本课程自己的材料:每周习题集、习题课、在线测验和考试信息指南 (Mankiw 是指定教材,所以概念逐章对应)。练习题由 AskSia 按本课程风格编写。考前请对照你自己的 Moodle 核实 -- 不同届之间细节会变。 - AskSia Library . ECB1101 · 双语 Bilingual THE BLUEPRINT - THE EXAM BLUEPRINT EXAM . 50% OF GRADE Where every mark lives 每一分都有出处 Half your grade, three sections, and 40 marks of graphs you draw by hand 占一半成绩、三个部分、40分手绘图 IN ONE LINE The final exam is 50% of your unit mark: 100 marks, 2 hours 10 minutes, closed book, covering Weeks 1-11. There is no hurdle - but half your grade, and the biggest block of marks (Section C, 40 marks of hand-drawn graphs), ride on it. 期末考试(final exam)占你课程成绩的 50%:100分,2 小时10分钟,闭卷,覆盖第1-11周。没有及格门槛(hurdle) -- 但你一半的成绩,以及分值最大的一块(C 部分,40分手绘图),都押在它上面。 50% FINAL EXAM 期末考试 100 marks TOTAL PAPER 整卷 2h10m CLOSED BOOK 闭卷 3 sections MCQ . SHORT . GRAPH 选择 · 简答 · 画图 The three exam sections 三个考试部分 Section What Marks A 30 multiple-choice questions 30 B 4 short-answer / calculation 30[3]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfC 2 hybrid graph-drawing + calculation 40 Section C is drawn by hand on blank paper and photographed & uploaded at the end. Calculator allowed; covers Weeks 1-11. C 部分在白纸上手绘,最后拍照并上传。允许使用计算器; 覆盖第1-11周。 The rest of your grade 成绩的其余部分 Component Weight Final exam 50% Individual assignment 20% In-class + online quizzes 30% ✓ The strategy this dictates 由此决定的策略 Section C is the single biggest block of marks (40) - and it is pure technique. Every Section-C answer is a diagram + a short calculation: draw the curves, mark the equilibrium, label every axis, curve and shift (with arrows), then shade and read off CS / PS / deadweight loss. Markers deduct for unlabelled graphs more than for arithmetic slips. The whole subject is a handful of models - demand & supply, surplus, taxes, costs, the four market structures - applied to fresh numbers and drawn. This book builds exactly that drawing-and-deriving skill, model by model. C 部分是分值最大的一块(40分) -- 而且全凭技巧。 每道 C 部分答案都是图+一段简短计算:画曲线、标 均衡、标注每条轴、曲线和移动(带箭头),然后着色并 读出 CS/ PS/ 无谓损失。批改者对未标注的图扣分 比对算术失误更狠。整个学科就是少数几个模型- 供求、剩余、税收、成本、四种市场结构 -- 套用到 新数字上并画出来。本书恰恰逐个模型地培养这种画 图与推导的能力。 AskSia Library . ECB1101 · 双语 Bilingual ★ What Section A & B reward A、B 部分奖励什么 A (MCQ): definitions and one-step calculations - the glossary and one-line recaps win these. B (short answer): a clean calculation with the right formula stated. Show the working; a stated formula + steps earns marks even if the final number slips. A(MCQ): 定义和一步计算 -- 词汇表和一行回顾就能 拿下。B(简答):一段干净的计算,写出正确公式。把 过程写出来;写出的公式加步骤即便最终数字出错也 能得分。 AskSia Library . ECB1101 · 双语 Bilingual CONTENTS - CONTENTS The whole subject, in Monash's order 整门课,按 Monash 的顺序 Eleven topics -> one exam-ready book 十一个主题 →一本应考书 Ch Topic Core idea
- Section B：4 short-answer / calculation（30 分）（写公式 + 算）[1]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdf你已经上过讲座和习题课。凭记 忆重画每张图,再遮住答案做练 习库。“考试招式”框展示了批改 者奖励的步骤。 C 3 . EXAM 3· 考试(EXAM) It's SWOTVAC. The one-line recap and glossary are your map. The blueprint overleaf shows where the marks sit - and why Section C (graphs) decides your grade. 到了SWOTVAC(考前复习周)。 那一行回顾和词汇表就是你的地 图。背面的蓝图展示分值落在哪 里 -- 以及为何 C 部分(图)决定 你的成绩。 i How this book was built 本书是如何编成的 Every model, diagram and worked number here is grounded in this unit's own materials: the weekly problem sets, workshops, online quizzes and the exam information guide (Mankiw is the set text, so the concepts line up chapter- for-chapter). Practice problems are AskSia-authored in the unit's style. Verify against your own Moodle before the exam - details shift between cohorts. 这里的每个模型、每张图和每个例题数字都扎根于本课程自己的材料:每周习题集、习题课、在线测验和考试信息指南 (Mankiw 是指定教材,所以概念逐章对应)。练习题由 AskSia 按本课程风格编写。考前请对照你自己的 Moodle 核实 -- 不同届之间细节会变。 - AskSia Library . ECB1101 · 双语 Bilingual THE BLUEPRINT - THE EXAM BLUEPRINT EXAM . 50% OF GRADE Where every mark lives 每一分都有出处 Half your grade, three sections, and 40 marks of graphs you draw by hand 占一半成绩、三个部分、40分手绘图 IN ONE LINE The final exam is 50% of your unit mark: 100 marks, 2 hours 10 minutes, closed book, covering Weeks 1-11. There is no hurdle - but half your grade, and the biggest block of marks (Section C, 40 marks of hand-drawn graphs), ride on it. 期末考试(final exam)占你课程成绩的 50%:100分,2 小时10分钟,闭卷,覆盖第1-11周。没有及格门槛(hurdle) -- 但你一半的成绩,以及分值最大的一块(C 部分,40分手绘图),都押在它上面。 50% FINAL EXAM 期末考试 100 marks TOTAL PAPER 整卷 2h10m CLOSED BOOK 闭卷 3 sections MCQ . SHORT . GRAPH 选择 · 简答 · 画图 The three exam sections 三个考试部分 Section What Marks A 30 multiple-choice questions 30 B 4 short-answer / calculation 30[3]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfC 2 hybrid graph-drawing + calculation 40 Section C is drawn by hand on blank paper and photographed & uploaded at the end. Calculator allowed; covers Weeks 1-11. C 部分在白纸上手绘,最后拍照并上传。允许使用计算器; 覆盖第1-11周。 The rest of your grade 成绩的其余部分 Component Weight Final exam 50% Individual assignment 20% In-class + online quizzes 30% ✓ The strategy this dictates 由此决定的策略 Section C is the single biggest block of marks (40) - and it is pure technique. Every Section-C answer is a diagram + a short calculation: draw the curves, mark the equilibrium, label every axis, curve and shift (with arrows), then shade and read off CS / PS / deadweight loss. Markers deduct for unlabelled graphs more than for arithmetic slips. The whole subject is a handful of models - demand & supply, surplus, taxes, costs, the four market structures - applied to fresh numbers and drawn. This book builds exactly that drawing-and-deriving skill, model by model. C 部分是分值最大的一块(40分) -- 而且全凭技巧。 每道 C 部分答案都是图+一段简短计算:画曲线、标 均衡、标注每条轴、曲线和移动(带箭头),然后着色并 读出 CS/ PS/ 无谓损失。批改者对未标注的图扣分 比对算术失误更狠。整个学科就是少数几个模型- 供求、剩余、税收、成本、四种市场结构 -- 套用到 新数字上并画出来。本书恰恰逐个模型地培养这种画 图与推导的能力。 AskSia Library . ECB1101 · 双语 Bilingual ★ What Section A & B reward A、B 部分奖励什么 A (MCQ): definitions and one-step calculations - the glossary and one-line recaps win these. B (short answer): a clean calculation with the right formula stated. Show the working; a stated formula + steps earns marks even if the final number slips. A(MCQ): 定义和一步计算 -- 词汇表和一行回顾就能 拿下。B(简答):一段干净的计算,写出正确公式。把 过程写出来;写出的公式加步骤即便最终数字出错也 能得分。 AskSia Library . ECB1101 · 双语 Bilingual CONTENTS - CONTENTS The whole subject, in Monash's order 整门课,按 Monash 的顺序 Eleven topics -> one exam-ready book 十一个主题 →一本应考书 Ch Topic Core idea
- Section C：2 hybrid graph-drawing + calculation（40 分）（手绘图 + 小计算）[3]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfC 2 hybrid graph-drawing + calculation 40 Section C is drawn by hand on blank paper and photographed & uploaded at the end. Calculator allowed; covers Weeks 1-11. C 部分在白纸上手绘,最后拍照并上传。允许使用计算器; 覆盖第1-11周。 The rest of your grade 成绩的其余部分 Component Weight Final exam 50% Individual assignment 20% In-class + online quizzes 30% ✓ The strategy this dictates 由此决定的策略 Section C is the single biggest block of marks (40) - and it is pure technique. Every Section-C answer is a diagram + a short calculation: draw the curves, mark the equilibrium, label every axis, curve and shift (with arrows), then shade and read off CS / PS / deadweight loss. Markers deduct for unlabelled graphs more than for arithmetic slips. The whole subject is a handful of models - demand & supply, surplus, taxes, costs, the four market structures - applied to fresh numbers and drawn. This book builds exactly that drawing-and-deriving skill, model by model. C 部分是分值最大的一块(40分) -- 而且全凭技巧。 每道 C 部分答案都是图+一段简短计算:画曲线、标 均衡、标注每条轴、曲线和移动(带箭头),然后着色并 读出 CS/ PS/ 无谓损失。批改者对未标注的图扣分 比对算术失误更狠。整个学科就是少数几个模型- 供求、剩余、税收、成本、四种市场结构 -- 套用到 新数字上并画出来。本书恰恰逐个模型地培养这种画 图与推导的能力。 AskSia Library . ECB1101 · 双语 Bilingual ★ What Section A & B reward A、B 部分奖励什么 A (MCQ): definitions and one-step calculations - the glossary and one-line recaps win these. B (short answer): a clean calculation with the right formula stated. Show the working; a stated formula + steps earns marks even if the final number slips. A(MCQ): 定义和一步计算 -- 词汇表和一行回顾就能 拿下。B(简答):一段干净的计算,写出正确公式。把 过程写出来;写出的公式加步骤即便最终数字出错也 能得分。 AskSia Library . ECB1101 · 双语 Bilingual CONTENTS - CONTENTS The whole subject, in Monash's order 整门课,按 Monash 的顺序 Eleven topics -> one exam-ready book 十一个主题 →一本应考书 Ch Topic Core idea
- 关键结论：Section C（40 分手绘图）决定成绩上限，而且是“纯技术活”。[1]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdf你已经上过讲座和习题课。凭记 忆重画每张图,再遮住答案做练 习库。“考试招式”框展示了批改 者奖励的步骤。 C 3 . EXAM 3· 考试(EXAM) It's SWOTVAC. The one-line recap and glossary are your map. The blueprint overleaf shows where the marks sit - and why Section C (graphs) decides your grade. 到了SWOTVAC(考前复习周)。 那一行回顾和词汇表就是你的地 图。背面的蓝图展示分值落在哪 里 -- 以及为何 C 部分(图)决定 你的成绩。 i How this book was built 本书是如何编成的 Every model, diagram and worked number here is grounded in this unit's own materials: the weekly problem sets, workshops, online quizzes and the exam information guide (Mankiw is the set text, so the concepts line up chapter- for-chapter). Practice problems are AskSia-authored in the unit's style. Verify against your own Moodle before the exam - details shift between cohorts. 这里的每个模型、每张图和每个例题数字都扎根于本课程自己的材料:每周习题集、习题课、在线测验和考试信息指南 (Mankiw 是指定教材,所以概念逐章对应)。练习题由 AskSia 按本课程风格编写。考前请对照你自己的 Moodle 核实 -- 不同届之间细节会变。 - AskSia Library . ECB1101 · 双语 Bilingual THE BLUEPRINT - THE EXAM BLUEPRINT EXAM . 50% OF GRADE Where every mark lives 每一分都有出处 Half your grade, three sections, and 40 marks of graphs you draw by hand 占一半成绩、三个部分、40分手绘图 IN ONE LINE The final exam is 50% of your unit mark: 100 marks, 2 hours 10 minutes, closed book, covering Weeks 1-11. There is no hurdle - but half your grade, and the biggest block of marks (Section C, 40 marks of hand-drawn graphs), ride on it. 期末考试(final exam)占你课程成绩的 50%:100分,2 小时10分钟,闭卷,覆盖第1-11周。没有及格门槛(hurdle) -- 但你一半的成绩,以及分值最大的一块(C 部分,40分手绘图),都押在它上面。 50% FINAL EXAM 期末考试 100 marks TOTAL PAPER 整卷 2h10m CLOSED BOOK 闭卷 3 sections MCQ . SHORT . GRAPH 选择 · 简答 · 画图 The three exam sections 三个考试部分 Section What Marks A 30 multiple-choice questions 30 B 4 short-answer / calculation 30[3]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfC 2 hybrid graph-drawing + calculation 40 Section C is drawn by hand on blank paper and photographed & uploaded at the end. Calculator allowed; covers Weeks 1-11. C 部分在白纸上手绘,最后拍照并上传。允许使用计算器; 覆盖第1-11周。 The rest of your grade 成绩的其余部分 Component Weight Final exam 50% Individual assignment 20% In-class + online quizzes 30% ✓ The strategy this dictates 由此决定的策略 Section C is the single biggest block of marks (40) - and it is pure technique. Every Section-C answer is a diagram + a short calculation: draw the curves, mark the equilibrium, label every axis, curve and shift (with arrows), then shade and read off CS / PS / deadweight loss. Markers deduct for unlabelled graphs more than for arithmetic slips. The whole subject is a handful of models - demand & supply, surplus, taxes, costs, the four market structures - applied to fresh numbers and drawn. This book builds exactly that drawing-and-deriving skill, model by model. C 部分是分值最大的一块(40分) -- 而且全凭技巧。 每道 C 部分答案都是图+一段简短计算:画曲线、标 均衡、标注每条轴、曲线和移动(带箭头),然后着色并 读出 CS/ PS/ 无谓损失。批改者对未标注的图扣分 比对算术失误更狠。整个学科就是少数几个模型- 供求、剩余、税收、成本、四种市场结构 -- 套用到 新数字上并画出来。本书恰恰逐个模型地培养这种画 图与推导的能力。 AskSia Library . ECB1101 · 双语 Bilingual ★ What Section A & B reward A、B 部分奖励什么 A (MCQ): definitions and one-step calculations - the glossary and one-line recaps win these. B (short answer): a clean calculation with the right formula stated. Show the working; a stated formula + steps earns marks even if the final number slips. A(MCQ): 定义和一步计算 -- 词汇表和一行回顾就能 拿下。B(简答):一段干净的计算,写出正确公式。把 过程写出来;写出的公式加步骤即便最终数字出错也 能得分。 AskSia Library . ECB1101 · 双语 Bilingual CONTENTS - CONTENTS The whole subject, in Monash's order 整门课,按 Monash 的顺序 Eleven topics -> one exam-ready book 十一个主题 →一本应考书 Ch Topic Core idea
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时间分配（按分配速算，避免最后来不及画图）
- 经验节奏：约 1.3 分钟 / 1 分（100 分 / 130 分钟）。[2]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfBudget ~1. 3 minutes per mark. Do Section A (30 MCQ) fast and bank it, then the four Section B short-answers, and protect time for Section C - it is 40 marks and the hand-drawn graphs are scanned after time, so the drawing must be finished in the room. If a calculation stalls, still draw the graph and state the rule: partial method earns partial marks. There is no exam hurdle - every mark just adds to your aggregate. 按 ** 每分约 1. 3 分钟 ** 分配。A部分(30道选择题)快速做完先把分收下,再做四道 B 部分简答,并 ** 为 C 部分留足 时间 **-- 它有 ** 40 分 ** ,手绘图在交卷后扫描评分,所以 ** 图必须在考场内画完 **。 若某项计算卡住,仍要 ** 画图 并写出规则 **: 方法过程能得部分分 。** 本考试没有及格门槛 **-- 每一分都直接计入你的总成绩。 AskSia Library . ECB1101 · 双语 Bilingual Set Qd = Qs. Find the wedge. Shade the triangle. Label everything. You have drilled this - walk in and do it. 令 Qd=Qs。找出税楔。给三角形阴影。把一切都标注好。你已反复练过这套 -- 走进考场,把它做出来。 I EXAM MORNING . ECB1101 AskSia Library . ECB1101 · 双语 Bilingual AskSia Library A+ COURSE PLAYBOOK MONASH BUSINESS SCHOOL SEMESTER 1 · 2026 THE COMPLETE EXAM BIBLE Introductory Microeconomics 微观经济学导论 ONE SUBJECT · EVERY GRAPH, EVERY MODEL, EVERY MARK. 一门课 · 每张图、每个模型、每一分都拿下 ECB1101 . MONASH UNIVERSITY 中英双语版 · BILINGUAL EDITION 英文主讲,中文随行 一 考试要点与术语保留英文原词 Built from this unit's own problem sets, workshops, quizzes and exam guide. Teaches each model from first principles, draws every diagram, then drills it to exam standard - because 50% of your grade rides on one 2-hour exam, and 40 of its 100 marks are graphs you draw by hand. For personal study Not affiliated with or endorsed by Monash takedowns@asksia. ai PREFACE - HOW TO USE THIS BOOK Three students, one book 三位学生,一本书 Wherever you are right now, start here 无论你现在在哪一步,从这里开始 This is not lecture notes. It is a complete, self-contained course in every model ECB1101 tests - every curve drawn, every result derived - written so the same pages serve you three times across the semester. 这不是课堂笔记,而是一套完整、自足的课程,覆盖 ECB1101 考察的每一个模型 -- 每条曲线都画出、每个结论都推导出 -- 这样同样的篇幅能在整个学期里为你服务三次。 A 1 . LEARN 1 · 学习(LEARN) You haven't watched the lecture. Read a chapter top to bottom. Each concept opens with a one-line takeaway and a labelled diagram, then a worked example with real numbers. You can learn the model here cold. 你还没看过讲座。把一章从头读 到尾。每个概念以一句要点和一 张带标注的图开场,然后是一个 带真实数字的例题。你可以在这 里从零学会模型。 B 2 . REVISE 2 · 复习(REVISE) You've done the lecture and workshop. Re-draw each diagram from memory, then work the practice bank with solutions covered. The "exam move" boxes show the steps markers reward.
- 建议顺序：
- C 部分特别提醒：手绘图最后拍照上传；交卷后扫描评分，所以图必须在场内画完。[2]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfBudget ~1. 3 minutes per mark. Do Section A (30 MCQ) fast and bank it, then the four Section B short-answers, and protect time for Section C - it is 40 marks and the hand-drawn graphs are scanned after time, so the drawing must be finished in the room. If a calculation stalls, still draw the graph and state the rule: partial method earns partial marks. There is no exam hurdle - every mark just adds to your aggregate. 按 ** 每分约 1. 3 分钟 ** 分配。A部分(30道选择题)快速做完先把分收下,再做四道 B 部分简答,并 ** 为 C 部分留足 时间 **-- 它有 ** 40 分 ** ,手绘图在交卷后扫描评分,所以 ** 图必须在考场内画完 **。 若某项计算卡住,仍要 ** 画图 并写出规则 **: 方法过程能得部分分 。** 本考试没有及格门槛 **-- 每一分都直接计入你的总成绩。 AskSia Library . ECB1101 · 双语 Bilingual Set Qd = Qs. Find the wedge. Shade the triangle. Label everything. You have drilled this - walk in and do it. 令 Qd=Qs。找出税楔。给三角形阴影。把一切都标注好。你已反复练过这套 -- 走进考场,把它做出来。 I EXAM MORNING . ECB1101 AskSia Library . ECB1101 · 双语 Bilingual AskSia Library A+ COURSE PLAYBOOK MONASH BUSINESS SCHOOL SEMESTER 1 · 2026 THE COMPLETE EXAM BIBLE Introductory Microeconomics 微观经济学导论 ONE SUBJECT · EVERY GRAPH, EVERY MODEL, EVERY MARK. 一门课 · 每张图、每个模型、每一分都拿下 ECB1101 . MONASH UNIVERSITY 中英双语版 · BILINGUAL EDITION 英文主讲,中文随行 一 考试要点与术语保留英文原词 Built from this unit's own problem sets, workshops, quizzes and exam guide. Teaches each model from first principles, draws every diagram, then drills it to exam standard - because 50% of your grade rides on one 2-hour exam, and 40 of its 100 marks are graphs you draw by hand. For personal study Not affiliated with or endorsed by Monash takedowns@asksia. ai PREFACE - HOW TO USE THIS BOOK Three students, one book 三位学生,一本书 Wherever you are right now, start here 无论你现在在哪一步,从这里开始 This is not lecture notes. It is a complete, self-contained course in every model ECB1101 tests - every curve drawn, every result derived - written so the same pages serve you three times across the semester. 这不是课堂笔记,而是一套完整、自足的课程,覆盖 ECB1101 考察的每一个模型 -- 每条曲线都画出、每个结论都推导出 -- 这样同样的篇幅能在整个学期里为你服务三次。 A 1 . LEARN 1 · 学习(LEARN) You haven't watched the lecture. Read a chapter top to bottom. Each concept opens with a one-line takeaway and a labelled diagram, then a worked example with real numbers. You can learn the model here cold. 你还没看过讲座。把一章从头读 到尾。每个概念以一句要点和一 张带标注的图开场,然后是一个 带真实数字的例题。你可以在这 里从零学会模型。 B 2 . REVISE 2 · 复习(REVISE) You've done the lecture and workshop. Re-draw each diagram from memory, then work the practice bank with solutions covered. The "exam move" boxes show the steps markers reward.[3]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfC 2 hybrid graph-drawing + calculation 40 Section C is drawn by hand on blank paper and photographed & uploaded at the end. Calculator allowed; covers Weeks 1-11. C 部分在白纸上手绘,最后拍照并上传。允许使用计算器; 覆盖第1-11周。 The rest of your grade 成绩的其余部分 Component Weight Final exam 50% Individual assignment 20% In-class + online quizzes 30% ✓ The strategy this dictates 由此决定的策略 Section C is the single biggest block of marks (40) - and it is pure technique. Every Section-C answer is a diagram + a short calculation: draw the curves, mark the equilibrium, label every axis, curve and shift (with arrows), then shade and read off CS / PS / deadweight loss. Markers deduct for unlabelled graphs more than for arithmetic slips. The whole subject is a handful of models - demand & supply, surplus, taxes, costs, the four market structures - applied to fresh numbers and drawn. This book builds exactly that drawing-and-deriving skill, model by model. C 部分是分值最大的一块(40分) -- 而且全凭技巧。 每道 C 部分答案都是图+一段简短计算:画曲线、标 均衡、标注每条轴、曲线和移动(带箭头),然后着色并 读出 CS/ PS/ 无谓损失。批改者对未标注的图扣分 比对算术失误更狠。整个学科就是少数几个模型- 供求、剩余、税收、成本、四种市场结构 -- 套用到 新数字上并画出来。本书恰恰逐个模型地培养这种画 图与推导的能力。 AskSia Library . ECB1101 · 双语 Bilingual ★ What Section A & B reward A、B 部分奖励什么 A (MCQ): definitions and one-step calculations - the glossary and one-line recaps win these. B (short answer): a clean calculation with the right formula stated. Show the working; a stated formula + steps earns marks even if the final number slips. A(MCQ): 定义和一步计算 -- 词汇表和一行回顾就能 拿下。B(简答):一段干净的计算,写出正确公式。把 过程写出来;写出的公式加步骤即便最终数字出错也 能得分。 AskSia Library . ECB1101 · 双语 Bilingual CONTENTS - CONTENTS The whole subject, in Monash's order 整门课,按 Monash 的顺序 Eleven topics -> one exam-ready book 十一个主题 →一本应考书 Ch Topic Core idea
-
“拿分规则”你要反着用（批改者扣分点）
- 批改者对 没标注的图扣分比算错数字更狠。所以你要：
- 计算卡住也要 先画图 + 写规则/公式 + 标注，过程分很稳。[2]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfBudget ~1. 3 minutes per mark. Do Section A (30 MCQ) fast and bank it, then the four Section B short-answers, and protect time for Section C - it is 40 marks and the hand-drawn graphs are scanned after time, so the drawing must be finished in the room. If a calculation stalls, still draw the graph and state the rule: partial method earns partial marks. There is no exam hurdle - every mark just adds to your aggregate. 按 ** 每分约 1. 3 分钟 ** 分配。A部分(30道选择题)快速做完先把分收下,再做四道 B 部分简答,并 ** 为 C 部分留足 时间 **-- 它有 ** 40 分 ** ,手绘图在交卷后扫描评分,所以 ** 图必须在考场内画完 **。 若某项计算卡住,仍要 ** 画图 并写出规则 **: 方法过程能得部分分 。** 本考试没有及格门槛 **-- 每一分都直接计入你的总成绩。 AskSia Library . ECB1101 · 双语 Bilingual Set Qd = Qs. Find the wedge. Shade the triangle. Label everything. You have drilled this - walk in and do it. 令 Qd=Qs。找出税楔。给三角形阴影。把一切都标注好。你已反复练过这套 -- 走进考场,把它做出来。 I EXAM MORNING . ECB1101 AskSia Library . ECB1101 · 双语 Bilingual AskSia Library A+ COURSE PLAYBOOK MONASH BUSINESS SCHOOL SEMESTER 1 · 2026 THE COMPLETE EXAM BIBLE Introductory Microeconomics 微观经济学导论 ONE SUBJECT · EVERY GRAPH, EVERY MODEL, EVERY MARK. 一门课 · 每张图、每个模型、每一分都拿下 ECB1101 . MONASH UNIVERSITY 中英双语版 · BILINGUAL EDITION 英文主讲,中文随行 一 考试要点与术语保留英文原词 Built from this unit's own problem sets, workshops, quizzes and exam guide. Teaches each model from first principles, draws every diagram, then drills it to exam standard - because 50% of your grade rides on one 2-hour exam, and 40 of its 100 marks are graphs you draw by hand. For personal study Not affiliated with or endorsed by Monash takedowns@asksia. ai PREFACE - HOW TO USE THIS BOOK Three students, one book 三位学生,一本书 Wherever you are right now, start here 无论你现在在哪一步,从这里开始 This is not lecture notes. It is a complete, self-contained course in every model ECB1101 tests - every curve drawn, every result derived - written so the same pages serve you three times across the semester. 这不是课堂笔记,而是一套完整、自足的课程,覆盖 ECB1101 考察的每一个模型 -- 每条曲线都画出、每个结论都推导出 -- 这样同样的篇幅能在整个学期里为你服务三次。 A 1 . LEARN 1 · 学习(LEARN) You haven't watched the lecture. Read a chapter top to bottom. Each concept opens with a one-line takeaway and a labelled diagram, then a worked example with real numbers. You can learn the model here cold. 你还没看过讲座。把一章从头读 到尾。每个概念以一句要点和一 张带标注的图开场,然后是一个 带真实数字的例题。你可以在这 里从零学会模型。 B 2 . REVISE 2 · 复习(REVISE) You've done the lecture and workshop. Re-draw each diagram from memory, then work the practice bank with solutions covered. The "exam move" boxes show the steps markers reward.[3]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfC 2 hybrid graph-drawing + calculation 40 Section C is drawn by hand on blank paper and photographed & uploaded at the end. Calculator allowed; covers Weeks 1-11. C 部分在白纸上手绘,最后拍照并上传。允许使用计算器; 覆盖第1-11周。 The rest of your grade 成绩的其余部分 Component Weight Final exam 50% Individual assignment 20% In-class + online quizzes 30% ✓ The strategy this dictates 由此决定的策略 Section C is the single biggest block of marks (40) - and it is pure technique. Every Section-C answer is a diagram + a short calculation: draw the curves, mark the equilibrium, label every axis, curve and shift (with arrows), then shade and read off CS / PS / deadweight loss. Markers deduct for unlabelled graphs more than for arithmetic slips. The whole subject is a handful of models - demand & supply, surplus, taxes, costs, the four market structures - applied to fresh numbers and drawn. This book builds exactly that drawing-and-deriving skill, model by model. C 部分是分值最大的一块(40分) -- 而且全凭技巧。 每道 C 部分答案都是图+一段简短计算:画曲线、标 均衡、标注每条轴、曲线和移动(带箭头),然后着色并 读出 CS/ PS/ 无谓损失。批改者对未标注的图扣分 比对算术失误更狠。整个学科就是少数几个模型- 供求、剩余、税收、成本、四种市场结构 -- 套用到 新数字上并画出来。本书恰恰逐个模型地培养这种画 图与推导的能力。 AskSia Library . ECB1101 · 双语 Bilingual ★ What Section A & B reward A、B 部分奖励什么 A (MCQ): definitions and one-step calculations - the glossary and one-line recaps win these. B (short answer): a clean calculation with the right formula stated. Show the working; a stated formula + steps earns marks even if the final number slips. A(MCQ): 定义和一步计算 -- 词汇表和一行回顾就能 拿下。B(简答):一段干净的计算,写出正确公式。把 过程写出来;写出的公式加步骤即便最终数字出错也 能得分。 AskSia Library . ECB1101 · 双语 Bilingual CONTENTS - CONTENTS The whole subject, in Monash's order 整门课,按 Monash 的顺序 Eleven topics -> one exam-ready book 十一个主题 →一本应考书 Ch Topic Core idea
- A/B/C 各自奖励什么：
- A：定义 + 一步判断（靠词汇表/一行回顾）[3]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfC 2 hybrid graph-drawing + calculation 40 Section C is drawn by hand on blank paper and photographed & uploaded at the end. Calculator allowed; covers Weeks 1-11. C 部分在白纸上手绘,最后拍照并上传。允许使用计算器; 覆盖第1-11周。 The rest of your grade 成绩的其余部分 Component Weight Final exam 50% Individual assignment 20% In-class + online quizzes 30% ✓ The strategy this dictates 由此决定的策略 Section C is the single biggest block of marks (40) - and it is pure technique. Every Section-C answer is a diagram + a short calculation: draw the curves, mark the equilibrium, label every axis, curve and shift (with arrows), then shade and read off CS / PS / deadweight loss. Markers deduct for unlabelled graphs more than for arithmetic slips. The whole subject is a handful of models - demand & supply, surplus, taxes, costs, the four market structures - applied to fresh numbers and drawn. This book builds exactly that drawing-and-deriving skill, model by model. C 部分是分值最大的一块(40分) -- 而且全凭技巧。 每道 C 部分答案都是图+一段简短计算:画曲线、标 均衡、标注每条轴、曲线和移动(带箭头),然后着色并 读出 CS/ PS/ 无谓损失。批改者对未标注的图扣分 比对算术失误更狠。整个学科就是少数几个模型- 供求、剩余、税收、成本、四种市场结构 -- 套用到 新数字上并画出来。本书恰恰逐个模型地培养这种画 图与推导的能力。 AskSia Library . ECB1101 · 双语 Bilingual ★ What Section A & B reward A、B 部分奖励什么 A (MCQ): definitions and one-step calculations - the glossary and one-line recaps win these. B (short answer): a clean calculation with the right formula stated. Show the working; a stated formula + steps earns marks even if the final number slips. A(MCQ): 定义和一步计算 -- 词汇表和一行回顾就能 拿下。B(简答):一段干净的计算,写出正确公式。把 过程写出来;写出的公式加步骤即便最终数字出错也 能得分。 AskSia Library . ECB1101 · 双语 Bilingual CONTENTS - CONTENTS The whole subject, in Monash's order 整门课,按 Monash 的顺序 Eleven topics -> one exam-ready book 十一个主题 →一本应考书 Ch Topic Core idea
- B：干净的计算 + 写出公式 + 过程（就算最后数滑了也有分）[3]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfC 2 hybrid graph-drawing + calculation 40 Section C is drawn by hand on blank paper and photographed & uploaded at the end. Calculator allowed; covers Weeks 1-11. C 部分在白纸上手绘,最后拍照并上传。允许使用计算器; 覆盖第1-11周。 The rest of your grade 成绩的其余部分 Component Weight Final exam 50% Individual assignment 20% In-class + online quizzes 30% ✓ The strategy this dictates 由此决定的策略 Section C is the single biggest block of marks (40) - and it is pure technique. Every Section-C answer is a diagram + a short calculation: draw the curves, mark the equilibrium, label every axis, curve and shift (with arrows), then shade and read off CS / PS / deadweight loss. Markers deduct for unlabelled graphs more than for arithmetic slips. The whole subject is a handful of models - demand & supply, surplus, taxes, costs, the four market structures - applied to fresh numbers and drawn. This book builds exactly that drawing-and-deriving skill, model by model. C 部分是分值最大的一块(40分) -- 而且全凭技巧。 每道 C 部分答案都是图+一段简短计算:画曲线、标 均衡、标注每条轴、曲线和移动(带箭头),然后着色并 读出 CS/ PS/ 无谓损失。批改者对未标注的图扣分 比对算术失误更狠。整个学科就是少数几个模型- 供求、剩余、税收、成本、四种市场结构 -- 套用到 新数字上并画出来。本书恰恰逐个模型地培养这种画 图与推导的能力。 AskSia Library . ECB1101 · 双语 Bilingual ★ What Section A & B reward A、B 部分奖励什么 A (MCQ): definitions and one-step calculations - the glossary and one-line recaps win these. B (short answer): a clean calculation with the right formula stated. Show the working; a stated formula + steps earns marks even if the final number slips. A(MCQ): 定义和一步计算 -- 词汇表和一行回顾就能 拿下。B(简答):一段干净的计算,写出正确公式。把 过程写出来;写出的公式加步骤即便最终数字出错也 能得分。 AskSia Library . ECB1101 · 双语 Bilingual CONTENTS - CONTENTS The whole subject, in Monash's order 整门课,按 Monash 的顺序 Eleven topics -> one exam-ready book 十一个主题 →一本应考书 Ch Topic Core idea
- C：每题 = 图 + 小计算（画曲线、标均衡、标轴/曲线/移动箭头、涂 CS/PS/DWL）[3]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfC 2 hybrid graph-drawing + calculation 40 Section C is drawn by hand on blank paper and photographed & uploaded at the end. Calculator allowed; covers Weeks 1-11. C 部分在白纸上手绘,最后拍照并上传。允许使用计算器; 覆盖第1-11周。 The rest of your grade 成绩的其余部分 Component Weight Final exam 50% Individual assignment 20% In-class + online quizzes 30% ✓ The strategy this dictates 由此决定的策略 Section C is the single biggest block of marks (40) - and it is pure technique. Every Section-C answer is a diagram + a short calculation: draw the curves, mark the equilibrium, label every axis, curve and shift (with arrows), then shade and read off CS / PS / deadweight loss. Markers deduct for unlabelled graphs more than for arithmetic slips. The whole subject is a handful of models - demand & supply, surplus, taxes, costs, the four market structures - applied to fresh numbers and drawn. This book builds exactly that drawing-and-deriving skill, model by model. C 部分是分值最大的一块(40分) -- 而且全凭技巧。 每道 C 部分答案都是图+一段简短计算:画曲线、标 均衡、标注每条轴、曲线和移动(带箭头),然后着色并 读出 CS/ PS/ 无谓损失。批改者对未标注的图扣分 比对算术失误更狠。整个学科就是少数几个模型- 供求、剩余、税收、成本、四种市场结构 -- 套用到 新数字上并画出来。本书恰恰逐个模型地培养这种画 图与推导的能力。 AskSia Library . ECB1101 · 双语 Bilingual ★ What Section A & B reward A、B 部分奖励什么 A (MCQ): definitions and one-step calculations - the glossary and one-line recaps win these. B (short answer): a clean calculation with the right formula stated. Show the working; a stated formula + steps earns marks even if the final number slips. A(MCQ): 定义和一步计算 -- 词汇表和一行回顾就能 拿下。B(简答):一段干净的计算,写出正确公式。把 过程写出来;写出的公式加步骤即便最终数字出错也 能得分。 AskSia Library . ECB1101 · 双语 Bilingual CONTENTS - CONTENTS The whole subject, in Monash's order 整门课,按 Monash 的顺序 Eleven topics -> one exam-ready book 十一个主题 →一本应考书 Ch Topic Core idea
- 批改者对 没标注的图扣分比算错数字更狠。所以你要：
-
1）整门课其实就一条“考试计算链条”（你复习要练成肌肉记忆）
-
你要背到能脱口而出的一条链
- 几乎每道 B/C 题都长得像这样：
- 令 $Q_d=Q_s$ → 求 $(P^*,Q^*)$
- 算弹性（中点法）
- 算 CS/PS（都是三角形面积）
- 加政策（税/补贴/管制/外部性）→ 找“楔子 wedge”
- 算税收/福利变化/无谓损失 DWL
- 再加企业部分两条铁律：完全竞争 $P=MC$；垄断 $MR=MC$。[7]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfOne firm supplies the whole market most cheaply (large fixed cost, falling ATC). Monopolistic competition 垄断竞争 Many firms, differentiated products, free entry; P > MC but zero LR profit. AskSia Library . ECB1101 · 双语 Bilingual Term (EN) 中文 One-line meaning Product differentiation 产品差异化 Making your product distinct, giving each firm a little market power. Excess capacity 过剩产能 Monopolistic competitors produce below efficient scale (left of min ATC). Oligopoly 寡头垄断 A few interdependent firms; each one's choice affects the others. ✓ How to revise from this glossary 如何用这份术语表复习 Cover the right two columns and define each term from the English alone; then cover the English and recall it from the +X. Pay special attention to the pairs you can confuse - movement vs shift, CS vs PS, P = MC vs MR = MC, public good vs common resource, normal vs inferior. Knowing the contrast is what beats the Section-A distractors. 遮住右侧两列,仅凭英文定义每个术语;再遮住英文,凭 ** 中文 ** 回忆。特别留意 ** 易混淆的成对概念 **-- 移动 (movement)与移位(shift)、CS 与 PS、P =MC 与 MR= MC、公共物品(public good)与公共资源(common resource)、正常品(normal)与劣等品(inferior)。掌握其间的 ** 对比 ** 才是击败 A 部分干扰项的关键。 AskSia Library . ECB1101 · 双语 Bilingual PRACTICE . SECTION A - PRACTICE BANK DRILL TO EXAM STANDARD Drill the ECB1101 paper, with full solutions 演练 ECB1101 试卷,附完整解答 AskSia-authored, exam style - Section A MCQ, Section B calcs, Section C hybrids AskSia 原创、考试风格 -- A 部分选择题、B部分计算、C 部分综合题 IN ONE LINE Work each problem on paper first, then read the solution. The whole paper is one chain in disguise: set QD = Qs - elasticity - CS / PS - impose a policy - deadweight loss, plus the firm rules P = MC and MR = MC.[15]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdf每道题先在纸上做,再读答案。整张试卷其实是同一条链:令 QD=Qs→ 弹性→ CS / PS→ 施加政策→ 无谓损 失,外加企业法则 P=MC 和 MR =MC。 ★ How to use this bank 如何使用这个题库 Cover the solution. Recognition is not recall - work it before you read a line. Budget ~1. 3 min per mark (the real paper is 100 marks in 130 min). Always draw and fully label the Section C graph - axes, both curves, equilibrium, shifts with arrows, and the shaded CS / PS / DWL. ECB1101 deducts marks for unlabelled graphs, so these are the safest marks on the paper. Reconcile at the end: CS + PS + revenue + DWL must add back to the original total surplus. ** 遮住答案 。** 认得≠记得 -- 动笔做完再看任何一 行 。** 按每分约 1. 3 分钟分配时间 ** (真卷 130 分钟 100 分) 。** C 部分的图务必画出并完整标注 **-- 坐 标轴、两条曲线、均衡点、带箭头的移位,以及阴影 标出的 CS/ PS/ DWL。ECB1101 ** 对未标注的图扣 分 ** ,所以这些是全卷最稳的分 。** 最后核对 :** CS + PS+ 税收+ DWL 必须加总回原来的社会总剩余 (TS) i How this maps to the real exam 这如何对应真实考试 Section A = 30 MCQ (30 marks) - definitions and one-step calls (Q1-Q5 below). Section B = 4 short- answer with calculations (30 marks) - elasticity, surplus, tax DWL (B1-B3). Section C = 2 graph- drawing hybrids (40 marks) - a tax-with-DWL and a monopoly (C1-C2). Answers are usually whole numbers; a calculator is allowed. ** A 部分 ** = 30 道选择题(MCQ)(30分)––定义 与一步判断(下文 Q1-Q5) 。** B 部分 ** = 4 道带计 算的简答(30分)––弹性、剩余、税收 DWL (B1-B3) 。** C 部分 ** = 2 道画图综合题(40分) 一道含 DWL 的税收题和一道垄断题(C1-C2)。 答案通常是整数;允许使用计算器。 ✓ Marks track the real allocations 分值与真实分配一致 Each card shows its type and marks. Section C is 40 of 100 marks - leave time to draw. Stems are AskSia's own; methods and number ranges mirror ECB1101's problem sets and in-class quizzes. 每张卡片标明其类型与分值。C部分占 ** 100 分中的 40分 **-- 留足画图时间。题干为 AskSia 自编;方 法与数值范围对标 ECB1101 的习题集与课堂小测。 - A Section A - multiple choice (definitions & one-step) A A 部分 -- 选择题(定义与一步计算) AskSia Library . ECB1101 · 双语 Bilingual Budget about a minute each: pick the answer, then confirm you can say why every other option is wrong - that is how you beat the near-miss distractor. 每题预算约一分钟:选出答案,然后确认你能说出为什么其余每个选项都是错的 -- 这就是你击败近似干扰项的方法。 Q1 MCQ movement vs shift A bad frost destroys half the coffee crop, and the quantity of coffee bought falls. On the coffee demand- supply diagram this is best described as: 一场严重的霜冻毁掉了一半的咖啡作物,咖啡的购买量随之下降。在咖啡供求图上,这最好被描述为: (a) a leftward shift of the demand curve (b) a leftward shift of supply, with a movement along demand - correct (c) a movement along the supply curve only (d) a rightward shift of demand Why (b): the frost is a supply shock (input/harvest), so S shifts left; the higher price then moves buyers along a fixed demand curve. (a)/(d) demand shifts come only from non-price factors (income, tastes, related-good prices). (c) ignores the demand response that sets the new price. 选(b)的原因:霜冻是一次供给冲击(投入/收成),所以 S左移;随后更高的价格使买方沿着固定的需求曲线移动。(a)/(d)需 求移动只来自非价格因素(收入、偏好、相关品价格)。(c)忽略了设定新价格的需求反应。 - Q2 MCQ income & cross-price elasticity When incomes rise, households buy fewer bus tickets and more rideshare trips. Bus travel and rideshare are, respectively: 当收入上升时,家庭购买更少的公交车票和更多的网约车出行。公交出行与网约车分别是: (a) an inferior good; and substitutes for the bus - correct (b) a normal good; and complements[6]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfI deadweight loss of monopoly AskSia Library · ECB1101 · 双语 Bilingual ** (c) 有效产量与 DWL 。** P = MC: 120-Q =20→ ** Qc=100 ** (在 P=$20处)。垄断者把产量限制在 50. DWL = 1/2 x (Pm - MC) x (Qc - Qm) = 1/2 x (70 - 20) x (100 - 50) = 1/2 x 50 x 50 = ** 1,250 ** - > ** $1. 25m **. Read-back: Pm = 70 > MC = 20 - price exceeds marginal cost, the signature of market power; the gap drives the welfare loss. ** 回读 :** Pm = 70 > MC= 20→价格超过边际成本,这 是 ** 市场势力 ** 的标志;该缺口驱动了福利损失。 ★ What to LABEL for full marks 为拿满分该标注什么 Axes (Price $, Quantity). Three curves: demand D = AR, the steeper MR (same intercept, twice the slope), and MC. Mark the MR = MC crossing to locate Qm = 50, then read up to demand for Pm = $70 (dotted guides). Mark Qc = 100 where D meets MC. Shade the DWL triangle between D and MC, from Qm to Qc. ** 坐标轴 ** (价格 $,数量) 。** 三条曲线 :** 需求 D= AR、更陡的 ** MR ** (同截距、斜率两倍)和 ** MC **。 标出 ** MR = MC ** 交点以确定 ** Qm= 50 ** ,再向上读到需求曲线得 ** Pm = $70 ** (虚线辅助)。标出D 与 MC 相交处 的 ** Qc = 100 **。 在 D与 MC 之间、从 Qm到 Qc, ** 阴影标出 DWL 三角形 **。 ! Quantity off MR = MC; price off the demand curve 产量由 MR= MC 决定;价格沿需求曲线读出 The single most common monopoly error is reading the price straight off MR. MR = MC locates only the quantity; the price is then read up to demand. And MR = a - 2bQ has twice the slope of demand - not the same line. A change in fixed cost would move profit but not Pm or Qm (MR and MC are unchanged). 垄断题最常见的单一错误是直接从 MR 读出价格 。** MR = MC 只定数量 **; 价格要 ** 向上读到需求曲线 **。 而 MR = a -2bQ 的斜率是需求的 ** 两倍 **-- 并非同一条线。固定成本的变化会改变利润,但 ** 不会 ** 改变Pm或Qm (MR 与 MC 不变)。 AskSia Library . ECB1101 · 双语 Bilingual EXAM MORNING - EXAM MORNING THE LAST HOUR If you remember nothing else 若别的都忘了,记住这些 Six reminders across the subject - read once, walk in, do it 全课六条提醒 -- 读一遍,进考场,照做 IN ONE LINE Set QD = Qs. Find the wedge. Shade the triangle. Label every axis, curve and shift. You have drilled this - now bank the easy marks. 令 Qp=Qs。求出楔子。给三角形着色。标注每条轴、每条曲线和每次移动。你已经反复练过 -- 现在把这些容易的分 稳稳收下。 THE CORE FORMULAS 1 . The chain set Qp = Qs - P*, Q *; CS / PS are triangle areas; a tax adds a wedge; DWL = 1/2 x tax x AQ 2 . Elasticity midpoint E = [4Q / Q] + [4P / P]; inelastic (|E| < 1) - raise price for more total revenue 3 . Firms competition P = MC; monopoly MR = MC then price off demand; MR = a - 2bQ; P > MC - DWL i 1 . The calculation chain is one method 1 · 计算链条本身就是一套方法 Almost every Section B/C question is the same chain: set QD = Qs for P*, Q *; CS / PS are triangle areas (1/2 × base x height, base = Q*); a tax drives a wedge Pb - Ps = t; and DWL = 1/2 x t x AQ. Reconcile: CS + PS + revenue + DWL must add back to the original surplus. 几乎每道 B/C 部分题目都是同一条链 :** 令 Qp= Qs ** 求P *、 Q *;** CS /PS 是三角形面积 ** (1/2 × 底 × 高,底=Q*);税收造成 ** 税楔 ** Pb -Ps = t;以及 ** DWL = 1/2 x t x △Q **。 核对:CS+ PS + 税收 +DWL 必须加总回原始剩余。
- 宝典把它称为“计算链条本身就是一套方法”。[6]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfI deadweight loss of monopoly AskSia Library · ECB1101 · 双语 Bilingual ** (c) 有效产量与 DWL 。** P = MC: 120-Q =20→ ** Qc=100 ** (在 P=$20处)。垄断者把产量限制在 50. DWL = 1/2 x (Pm - MC) x (Qc - Qm) = 1/2 x (70 - 20) x (100 - 50) = 1/2 x 50 x 50 = ** 1,250 ** - > ** $1. 25m **. Read-back: Pm = 70 > MC = 20 - price exceeds marginal cost, the signature of market power; the gap drives the welfare loss. ** 回读 :** Pm = 70 > MC= 20→价格超过边际成本,这 是 ** 市场势力 ** 的标志;该缺口驱动了福利损失。 ★ What to LABEL for full marks 为拿满分该标注什么 Axes (Price $, Quantity). Three curves: demand D = AR, the steeper MR (same intercept, twice the slope), and MC. Mark the MR = MC crossing to locate Qm = 50, then read up to demand for Pm = $70 (dotted guides). Mark Qc = 100 where D meets MC. Shade the DWL triangle between D and MC, from Qm to Qc. ** 坐标轴 ** (价格 $,数量) 。** 三条曲线 :** 需求 D= AR、更陡的 ** MR ** (同截距、斜率两倍)和 ** MC **。 标出 ** MR = MC ** 交点以确定 ** Qm= 50 ** ,再向上读到需求曲线得 ** Pm = $70 ** (虚线辅助)。标出D 与 MC 相交处 的 ** Qc = 100 **。 在 D与 MC 之间、从 Qm到 Qc, ** 阴影标出 DWL 三角形 **。 ! Quantity off MR = MC; price off the demand curve 产量由 MR= MC 决定;价格沿需求曲线读出 The single most common monopoly error is reading the price straight off MR. MR = MC locates only the quantity; the price is then read up to demand. And MR = a - 2bQ has twice the slope of demand - not the same line. A change in fixed cost would move profit but not Pm or Qm (MR and MC are unchanged). 垄断题最常见的单一错误是直接从 MR 读出价格 。** MR = MC 只定数量 **; 价格要 ** 向上读到需求曲线 **。 而 MR = a -2bQ 的斜率是需求的 ** 两倍 **-- 并非同一条线。固定成本的变化会改变利润,但 ** 不会 ** 改变Pm或Qm (MR 与 MC 不变)。 AskSia Library . ECB1101 · 双语 Bilingual EXAM MORNING - EXAM MORNING THE LAST HOUR If you remember nothing else 若别的都忘了,记住这些 Six reminders across the subject - read once, walk in, do it 全课六条提醒 -- 读一遍,进考场,照做 IN ONE LINE Set QD = Qs. Find the wedge. Shade the triangle. Label every axis, curve and shift. You have drilled this - now bank the easy marks. 令 Qp=Qs。求出楔子。给三角形着色。标注每条轴、每条曲线和每次移动。你已经反复练过 -- 现在把这些容易的分 稳稳收下。 THE CORE FORMULAS 1 . The chain set Qp = Qs - P*, Q *; CS / PS are triangle areas; a tax adds a wedge; DWL = 1/2 x tax x AQ 2 . Elasticity midpoint E = [4Q / Q] + [4P / P]; inelastic (|E| < 1) - raise price for more total revenue 3 . Firms competition P = MC; monopoly MR = MC then price off demand; MR = a - 2bQ; P > MC - DWL i 1 . The calculation chain is one method 1 · 计算链条本身就是一套方法 Almost every Section B/C question is the same chain: set QD = Qs for P*, Q *; CS / PS are triangle areas (1/2 × base x height, base = Q*); a tax drives a wedge Pb - Ps = t; and DWL = 1/2 x t x AQ. Reconcile: CS + PS + revenue + DWL must add back to the original surplus. 几乎每道 B/C 部分题目都是同一条链 :** 令 Qp= Qs ** 求P *、 Q *;** CS /PS 是三角形面积 ** (1/2 × 底 × 高,底=Q*);税收造成 ** 税楔 ** Pb -Ps = t;以及 ** DWL = 1/2 x t x △Q **。 核对:CS+ PS + 税收 +DWL 必须加总回原始剩余。
- 几乎每道 B/C 题都长得像这样：
-
你要形成的“固定动作”（Section C 尤其吃这套）
- 先求均衡：无论后面是税、补贴、价格上限/下限，第一步永远是：
- 最后做核对（很像“送分 check”）：
- 福利核对（税题/福利题常用）：
- 复盘关系：$CS + PS + \text{revenue} + DWL$ 必须加回原来的 TS（检查你漏涂/漏算）。[6]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfI deadweight loss of monopoly AskSia Library · ECB1101 · 双语 Bilingual ** (c) 有效产量与 DWL 。** P = MC: 120-Q =20→ ** Qc=100 ** (在 P=$20处)。垄断者把产量限制在 50. DWL = 1/2 x (Pm - MC) x (Qc - Qm) = 1/2 x (70 - 20) x (100 - 50) = 1/2 x 50 x 50 = ** 1,250 ** - > ** $1. 25m **. Read-back: Pm = 70 > MC = 20 - price exceeds marginal cost, the signature of market power; the gap drives the welfare loss. ** 回读 :** Pm = 70 > MC= 20→价格超过边际成本,这 是 ** 市场势力 ** 的标志;该缺口驱动了福利损失。 ★ What to LABEL for full marks 为拿满分该标注什么 Axes (Price $, Quantity). Three curves: demand D = AR, the steeper MR (same intercept, twice the slope), and MC. Mark the MR = MC crossing to locate Qm = 50, then read up to demand for Pm = $70 (dotted guides). Mark Qc = 100 where D meets MC. Shade the DWL triangle between D and MC, from Qm to Qc. ** 坐标轴 ** (价格 $,数量) 。** 三条曲线 :** 需求 D= AR、更陡的 ** MR ** (同截距、斜率两倍)和 ** MC **。 标出 ** MR = MC ** 交点以确定 ** Qm= 50 ** ,再向上读到需求曲线得 ** Pm = $70 ** (虚线辅助)。标出D 与 MC 相交处 的 ** Qc = 100 **。 在 D与 MC 之间、从 Qm到 Qc, ** 阴影标出 DWL 三角形 **。 ! Quantity off MR = MC; price off the demand curve 产量由 MR= MC 决定;价格沿需求曲线读出 The single most common monopoly error is reading the price straight off MR. MR = MC locates only the quantity; the price is then read up to demand. And MR = a - 2bQ has twice the slope of demand - not the same line. A change in fixed cost would move profit but not Pm or Qm (MR and MC are unchanged). 垄断题最常见的单一错误是直接从 MR 读出价格 。** MR = MC 只定数量 **; 价格要 ** 向上读到需求曲线 **。 而 MR = a -2bQ 的斜率是需求的 ** 两倍 **-- 并非同一条线。固定成本的变化会改变利润,但 ** 不会 ** 改变Pm或Qm (MR 与 MC 不变)。 AskSia Library . ECB1101 · 双语 Bilingual EXAM MORNING - EXAM MORNING THE LAST HOUR If you remember nothing else 若别的都忘了,记住这些 Six reminders across the subject - read once, walk in, do it 全课六条提醒 -- 读一遍,进考场,照做 IN ONE LINE Set QD = Qs. Find the wedge. Shade the triangle. Label every axis, curve and shift. You have drilled this - now bank the easy marks. 令 Qp=Qs。求出楔子。给三角形着色。标注每条轴、每条曲线和每次移动。你已经反复练过 -- 现在把这些容易的分 稳稳收下。 THE CORE FORMULAS 1 . The chain set Qp = Qs - P*, Q *; CS / PS are triangle areas; a tax adds a wedge; DWL = 1/2 x tax x AQ 2 . Elasticity midpoint E = [4Q / Q] + [4P / P]; inelastic (|E| < 1) - raise price for more total revenue 3 . Firms competition P = MC; monopoly MR = MC then price off demand; MR = a - 2bQ; P > MC - DWL i 1 . The calculation chain is one method 1 · 计算链条本身就是一套方法 Almost every Section B/C question is the same chain: set QD = Qs for P*, Q *; CS / PS are triangle areas (1/2 × base x height, base = Q*); a tax drives a wedge Pb - Ps = t; and DWL = 1/2 x t x AQ. Reconcile: CS + PS + revenue + DWL must add back to the original surplus. 几乎每道 B/C 部分题目都是同一条链 :** 令 Qp= Qs ** 求P *、 Q *;** CS /PS 是三角形面积 ** (1/2 × 底 × 高,底=Q*);税收造成 ** 税楔 ** Pb -Ps = t;以及 ** DWL = 1/2 x t x △Q **。 核对:CS+ PS + 税收 +DWL 必须加总回原始剩余。[15]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdf每道题先在纸上做,再读答案。整张试卷其实是同一条链:令 QD=Qs→ 弹性→ CS / PS→ 施加政策→ 无谓损 失,外加企业法则 P=MC 和 MR =MC。 ★ How to use this bank 如何使用这个题库 Cover the solution. Recognition is not recall - work it before you read a line. Budget ~1. 3 min per mark (the real paper is 100 marks in 130 min). Always draw and fully label the Section C graph - axes, both curves, equilibrium, shifts with arrows, and the shaded CS / PS / DWL. ECB1101 deducts marks for unlabelled graphs, so these are the safest marks on the paper. Reconcile at the end: CS + PS + revenue + DWL must add back to the original total surplus. ** 遮住答案 。** 认得≠记得 -- 动笔做完再看任何一 行 。** 按每分约 1. 3 分钟分配时间 ** (真卷 130 分钟 100 分) 。** C 部分的图务必画出并完整标注 **-- 坐 标轴、两条曲线、均衡点、带箭头的移位,以及阴影 标出的 CS/ PS/ DWL。ECB1101 ** 对未标注的图扣 分 ** ,所以这些是全卷最稳的分 。** 最后核对 :** CS + PS+ 税收+ DWL 必须加总回原来的社会总剩余 (TS) i How this maps to the real exam 这如何对应真实考试 Section A = 30 MCQ (30 marks) - definitions and one-step calls (Q1-Q5 below). Section B = 4 short- answer with calculations (30 marks) - elasticity, surplus, tax DWL (B1-B3). Section C = 2 graph- drawing hybrids (40 marks) - a tax-with-DWL and a monopoly (C1-C2). Answers are usually whole numbers; a calculator is allowed. ** A 部分 ** = 30 道选择题(MCQ)(30分)––定义 与一步判断(下文 Q1-Q5) 。** B 部分 ** = 4 道带计 算的简答(30分)––弹性、剩余、税收 DWL (B1-B3) 。** C 部分 ** = 2 道画图综合题(40分) 一道含 DWL 的税收题和一道垄断题(C1-C2)。 答案通常是整数;允许使用计算器。 ✓ Marks track the real allocations 分值与真实分配一致 Each card shows its type and marks. Section C is 40 of 100 marks - leave time to draw. Stems are AskSia's own; methods and number ranges mirror ECB1101's problem sets and in-class quizzes. 每张卡片标明其类型与分值。C部分占 ** 100 分中的 40分 **-- 留足画图时间。题干为 AskSia 自编;方 法与数值范围对标 ECB1101 的习题集与课堂小测。 - A Section A - multiple choice (definitions & one-step) A A 部分 -- 选择题(定义与一步计算) AskSia Library . ECB1101 · 双语 Bilingual Budget about a minute each: pick the answer, then confirm you can say why every other option is wrong - that is how you beat the near-miss distractor. 每题预算约一分钟:选出答案,然后确认你能说出为什么其余每个选项都是错的 -- 这就是你击败近似干扰项的方法。 Q1 MCQ movement vs shift A bad frost destroys half the coffee crop, and the quantity of coffee bought falls. On the coffee demand- supply diagram this is best described as: 一场严重的霜冻毁掉了一半的咖啡作物,咖啡的购买量随之下降。在咖啡供求图上,这最好被描述为: (a) a leftward shift of the demand curve (b) a leftward shift of supply, with a movement along demand - correct (c) a movement along the supply curve only (d) a rightward shift of demand Why (b): the frost is a supply shock (input/harvest), so S shifts left; the higher price then moves buyers along a fixed demand curve. (a)/(d) demand shifts come only from non-price factors (income, tastes, related-good prices). (c) ignores the demand response that sets the new price. 选(b)的原因:霜冻是一次供给冲击(投入/收成),所以 S左移;随后更高的价格使买方沿着固定的需求曲线移动。(a)/(d)需 求移动只来自非价格因素(收入、偏好、相关品价格)。(c)忽略了设定新价格的需求反应。 - Q2 MCQ income & cross-price elasticity When incomes rise, households buy fewer bus tickets and more rideshare trips. Bus travel and rideshare are, respectively: 当收入上升时,家庭购买更少的公交车票和更多的网约车出行。公交出行与网约车分别是: (a) an inferior good; and substitutes for the bus - correct (b) a normal good; and complements
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Week 1 / Chapter 1：经济学思维方式（Section A 高频）
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必背定义（MCQ/判断题最爱）
- Scarcity（稀缺）：无限欲望 + 有限资源 → 必须选择。[5]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfOligopoly a few large brewers dominate Part 2 - trace Sleek Sneakers from short run to long run 第2 部分––追踪 Sleek Sneakers 从短期到长期 1 (a) Short run, earning profit. Sleek faces its own downward demand. It maximises at MR = MC -+ q*, reads P* off demand above ATC, and earns profit = (P *- ATC)xq* - the shaded rectangle of Fig 11. 1. Exactly like a monopoly. ** (a) 短期,盈利 。** Sleek 面对自身向下倾斜的需求。它在 ** MR = MC ** 处最大化 → q*,在 ATC 之上从 ** 需求曲 线读出 P *** ,赚取利润 =(P *- ATC)xq *-- 即 ** 图 11. 1 ** 的阴影矩形。与垄断完全一样。 2 (b) Long run, profit competed away. Profits attract new sneaker brands. Each entrant pulls customers from Sleek, shifting Sleek's demand curve left until it is tangent to ATC: P falls to ATC, profit = 0 - the tangency of Fig 11. 2. ** (b)长期,利润被竞争掉 。** 利润吸引新运动鞋品牌进入。每个进入者从 Sleek 抢走顾客,使 ** Sleek 的需求曲线左 移 ** 直到与 ** ATC 相切 **: P 降至 ATC,利润=0 -- 即 ** 图 11. 2 ** 的切点。 3 (c) Stronger differentiation. A distinctive style makes demand steeper / less elastic (higher price, bigger markup); if it cannot be copied it becomes a barrier to entry, letting Sleek hold positive long- run profit (toward the monopoly end). ** (c)更强的差异化 。** 独特的款式使需求 ** 更陡/弹性更小 ** (价格更高、加成更大);若 ** 无法被模仿 ** ,它便成为 ** 进入壁垒(barrier to entry) ** ,让 Sleek 维持 ** 长期正利润 ** (偏向垄断一端)。 ✓ Section-C drawing sequence C 部分画图顺序 (1) SR: D, MR, MC, ATC; q* at MR = MC, P* up on D; shade profit. (2) Arrow: demand shifts left as firms enter. (3) LR: demand tangent to ATC, P = ATC, It = O. Label every axis, curve and shift arrow. ** (1) ** 短期(SR):画 D、MR、MC、ATC; q* 在 MR = MC处,P*沿D 向上取 ;** 阴影标出利润 **。** (2) ** 箭头:企业进入时需求 ** 左移 **。** (3) ** 长期(LR):需求 ** 与 ATC 相切 ** ,P = ATC,π=0。每条坐标轴、曲 线和移动箭头都要标注。 AskSia Library . ECB1101 · 双语 Bilingual GLOSSARY 1/ 3 - GLOSSARY 术语表 · EVERY TERM Every term, EN ←中文 每个术语,英←中 The whole ECB1101 vocabulary on three pages - grouped by topic, with one-line meanings 整套 ECB1101 词汇三页讲完 -- 按主题分组,附一句释义 IN ONE LINE Every examinable ECB1101 term in one place, English +> > with a one-line meaning. Screenshot it. The Chinese column is a translation aid - the exam itself is in English. 把每一个会考到的 ECB1101 术语集中一处,英文←中文,附一行释义。截图保存。中文列是翻译辅助 -- 考试本身是 英文的。 Term (EN) 中文 One-line meaning Foundations - scarcity, choice, the PPF Scarcity 稀缺 Unlimited wants meet finite resources, so we must choose.[20]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdf★ How ECB1101 tests this ECB1101 如何考查这一点 Week 1 ideas surface as Section A multiple-choice and true/false concept checks: name the opportunity cost of a choice (ignoring sunk costs), read a point as efficient / inefficient / unattainable on a PPF, decide whether a statement is positive or normative, and apply the MB = MC rule. The recurring trap is confusing what you spent with what you gave up. 第1周的理念以 A 部分选择题和判断题概念检查出现:说出一个选择的机会成本(忽略沉没成本),把 PPF 上一个点读作 有效率/无效率/不可达,判断一句话是实证还是规范,并应用MB= MC 法则。反复出现的陷阱是把你花掉的与你放 弃的混为一谈。 1. 1 Scarcity & the economic problem 1. 1 稀缺与经济问题 Human wants are unlimited; the resources to satisfy them - time, labour, capital, land - are finite. That gap is scarcity, and it forces every individual, firm and society to choose. To choose one thing is, at the same instant, to choose not to do something else. Economics studies how scarce resources are allocated among competing uses, and the tool that values any choice is its opportunity cost. - 人的欲望无限;满足欲望的资源 -- 时间、劳动、资本、土地 -- 是有限的。这道缺口就是稀缺(scarcity),它迫使每个人、 每家企业和整个社会去选择。选择一件事,就在同一刻选择了不做另一件事。经济学研究稀缺资源如何在相互竞争的用途间配 置,而衡量任何选择的工具就是它的机会成本。 - 1. 2 Opportunity cost 1. 2 机会成本 AskSia Library · ECB1101 · 双语 Bilingual The opportunity cost of a choice is the value of the next-best alternative forgone - the single best thing you gave up to get what you chose. It is not the sum of everything you did not do, and it is not the dollar price on the tag. For students the biggest cost is usually time: the wage you could have earned, the study you could have done. 一个选择的机会成本(opportunity cost)是被放弃的次优选项的价值 -- 你为得到所选之物而放弃的那一件最好的东西。它不 是你没做的所有事之和,也不是标签上的金额。对学生而言最大的成本通常是时间:你本可赚到的工资、本可完成的学习。 DEFINITION opportunity cost = value of the next-best alternative forgone ! Sunk costs are not opportunity costs 沉没成本不是机会成本 A sunk cost is money already spent that cannot be recovered - a non-refundable ticket, last semester's fees. It is the same whatever you choose next, so it is irrelevant to the decision. Rational choice looks only forward: weigh the marginal benefit against the opportunity cost of the next action, and ignore what is already gone. 沉没成本(sunk cost)是已经花掉、无法收回的钱 -- 一张不可退的票、上学期的学费。无论你接下来怎么选它都一样, 所以它与决策无关。理性选择只向前看:权衡下一步行动的边际收益与机会成本,无视已经逝去的。 AskSia Library . ECB1101 · 双语 Bilingual CH 1 . PPF - CHAPTER 1 (CONT. ) The production possibility frontier 生产可能性边界 (PPF) Drawing scarcity, trade-offs and efficiency in one curve 用一条曲线画出稀缺、权衡与效率 1. 3 The PPF 1. 3 PPF The production possibility frontier (PPF) shows the maximum combinations of two goods an economy can produce when all resources are fully and efficiently used. It makes scarcity visible: to get more of one good you must move along the curve and give up some of the other - and that sacrifice is the opportunity cost. 生产可能性边界(PPF)展示了当所有资源被充分且有效利用 时,一个经济体能生产的两种商品的最大组合。它让稀缺可 见:要多生产一种商品,你必须沿着曲线移动、放弃一些另 一种 -- 而那份牺牲就是机会成本。 - On the curve - efficient (no waste; producing the most possible). 曲线 **** → ** 有效率 ** (无浪费;产出尽可能多)。
- Opportunity cost（机会成本）：你为选择某项而放弃的 “次优选项的价值”（只取那个“单一最好替代项”）。[20]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdf★ How ECB1101 tests this ECB1101 如何考查这一点 Week 1 ideas surface as Section A multiple-choice and true/false concept checks: name the opportunity cost of a choice (ignoring sunk costs), read a point as efficient / inefficient / unattainable on a PPF, decide whether a statement is positive or normative, and apply the MB = MC rule. The recurring trap is confusing what you spent with what you gave up. 第1周的理念以 A 部分选择题和判断题概念检查出现:说出一个选择的机会成本(忽略沉没成本),把 PPF 上一个点读作 有效率/无效率/不可达,判断一句话是实证还是规范,并应用MB= MC 法则。反复出现的陷阱是把你花掉的与你放 弃的混为一谈。 1. 1 Scarcity & the economic problem 1. 1 稀缺与经济问题 Human wants are unlimited; the resources to satisfy them - time, labour, capital, land - are finite. That gap is scarcity, and it forces every individual, firm and society to choose. To choose one thing is, at the same instant, to choose not to do something else. Economics studies how scarce resources are allocated among competing uses, and the tool that values any choice is its opportunity cost. - 人的欲望无限;满足欲望的资源 -- 时间、劳动、资本、土地 -- 是有限的。这道缺口就是稀缺(scarcity),它迫使每个人、 每家企业和整个社会去选择。选择一件事,就在同一刻选择了不做另一件事。经济学研究稀缺资源如何在相互竞争的用途间配 置,而衡量任何选择的工具就是它的机会成本。 - 1. 2 Opportunity cost 1. 2 机会成本 AskSia Library · ECB1101 · 双语 Bilingual The opportunity cost of a choice is the value of the next-best alternative forgone - the single best thing you gave up to get what you chose. It is not the sum of everything you did not do, and it is not the dollar price on the tag. For students the biggest cost is usually time: the wage you could have earned, the study you could have done. 一个选择的机会成本(opportunity cost)是被放弃的次优选项的价值 -- 你为得到所选之物而放弃的那一件最好的东西。它不 是你没做的所有事之和,也不是标签上的金额。对学生而言最大的成本通常是时间:你本可赚到的工资、本可完成的学习。 DEFINITION opportunity cost = value of the next-best alternative forgone ! Sunk costs are not opportunity costs 沉没成本不是机会成本 A sunk cost is money already spent that cannot be recovered - a non-refundable ticket, last semester's fees. It is the same whatever you choose next, so it is irrelevant to the decision. Rational choice looks only forward: weigh the marginal benefit against the opportunity cost of the next action, and ignore what is already gone. 沉没成本(sunk cost)是已经花掉、无法收回的钱 -- 一张不可退的票、上学期的学费。无论你接下来怎么选它都一样, 所以它与决策无关。理性选择只向前看:权衡下一步行动的边际收益与机会成本,无视已经逝去的。 AskSia Library . ECB1101 · 双语 Bilingual CH 1 . PPF - CHAPTER 1 (CONT. ) The production possibility frontier 生产可能性边界 (PPF) Drawing scarcity, trade-offs and efficiency in one curve 用一条曲线画出稀缺、权衡与效率 1. 3 The PPF 1. 3 PPF The production possibility frontier (PPF) shows the maximum combinations of two goods an economy can produce when all resources are fully and efficiently used. It makes scarcity visible: to get more of one good you must move along the curve and give up some of the other - and that sacrifice is the opportunity cost. 生产可能性边界(PPF)展示了当所有资源被充分且有效利用 时,一个经济体能生产的两种商品的最大组合。它让稀缺可 见:要多生产一种商品,你必须沿着曲线移动、放弃一些另 一种 -- 而那份牺牲就是机会成本。 - On the curve - efficient (no waste; producing the most possible). 曲线 **** → ** 有效率 ** (无浪费;产出尽可能多)。
- Sunk cost（沉没成本）：已经花掉且不可收回的钱；决策时应忽略。[20]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdf★ How ECB1101 tests this ECB1101 如何考查这一点 Week 1 ideas surface as Section A multiple-choice and true/false concept checks: name the opportunity cost of a choice (ignoring sunk costs), read a point as efficient / inefficient / unattainable on a PPF, decide whether a statement is positive or normative, and apply the MB = MC rule. The recurring trap is confusing what you spent with what you gave up. 第1周的理念以 A 部分选择题和判断题概念检查出现:说出一个选择的机会成本(忽略沉没成本),把 PPF 上一个点读作 有效率/无效率/不可达,判断一句话是实证还是规范,并应用MB= MC 法则。反复出现的陷阱是把你花掉的与你放 弃的混为一谈。 1. 1 Scarcity & the economic problem 1. 1 稀缺与经济问题 Human wants are unlimited; the resources to satisfy them - time, labour, capital, land - are finite. That gap is scarcity, and it forces every individual, firm and society to choose. To choose one thing is, at the same instant, to choose not to do something else. Economics studies how scarce resources are allocated among competing uses, and the tool that values any choice is its opportunity cost. - 人的欲望无限;满足欲望的资源 -- 时间、劳动、资本、土地 -- 是有限的。这道缺口就是稀缺(scarcity),它迫使每个人、 每家企业和整个社会去选择。选择一件事,就在同一刻选择了不做另一件事。经济学研究稀缺资源如何在相互竞争的用途间配 置,而衡量任何选择的工具就是它的机会成本。 - 1. 2 Opportunity cost 1. 2 机会成本 AskSia Library · ECB1101 · 双语 Bilingual The opportunity cost of a choice is the value of the next-best alternative forgone - the single best thing you gave up to get what you chose. It is not the sum of everything you did not do, and it is not the dollar price on the tag. For students the biggest cost is usually time: the wage you could have earned, the study you could have done. 一个选择的机会成本(opportunity cost)是被放弃的次优选项的价值 -- 你为得到所选之物而放弃的那一件最好的东西。它不 是你没做的所有事之和,也不是标签上的金额。对学生而言最大的成本通常是时间:你本可赚到的工资、本可完成的学习。 DEFINITION opportunity cost = value of the next-best alternative forgone ! Sunk costs are not opportunity costs 沉没成本不是机会成本 A sunk cost is money already spent that cannot be recovered - a non-refundable ticket, last semester's fees. It is the same whatever you choose next, so it is irrelevant to the decision. Rational choice looks only forward: weigh the marginal benefit against the opportunity cost of the next action, and ignore what is already gone. 沉没成本(sunk cost)是已经花掉、无法收回的钱 -- 一张不可退的票、上学期的学费。无论你接下来怎么选它都一样, 所以它与决策无关。理性选择只向前看:权衡下一步行动的边际收益与机会成本,无视已经逝去的。 AskSia Library . ECB1101 · 双语 Bilingual CH 1 . PPF - CHAPTER 1 (CONT. ) The production possibility frontier 生产可能性边界 (PPF) Drawing scarcity, trade-offs and efficiency in one curve 用一条曲线画出稀缺、权衡与效率 1. 3 The PPF 1. 3 PPF The production possibility frontier (PPF) shows the maximum combinations of two goods an economy can produce when all resources are fully and efficiently used. It makes scarcity visible: to get more of one good you must move along the curve and give up some of the other - and that sacrifice is the opportunity cost. 生产可能性边界(PPF)展示了当所有资源被充分且有效利用 时,一个经济体能生产的两种商品的最大组合。它让稀缺可 见:要多生产一种商品,你必须沿着曲线移动、放弃一些另 一种 -- 而那份牺牲就是机会成本。 - On the curve - efficient (no waste; producing the most possible). 曲线 **** → ** 有效率 ** (无浪费;产出尽可能多)。
- MB = MC（边际收益=边际成本）规则：任何“要不要多做一点”的题都用它。例：咖啡店是否再冲一杯：比较 MB 和 MC，直到 MB 降到等于 MC 才停。[9]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdf一家咖啡馆每杯咖啡卖 $5。冲下一杯的边际成本(咖啡豆、牛奶、纸杯、咖啡师的一分钟)是 $3。它该不该再冲一杯? 1 Identify MB of the next coffee = the $5 it sells for. 确定下一杯咖啡的 ** 边际收益(MB) **= 其售价 $5。 2 Identify MC of the next coffee = the $3 of extra inputs. (Yesterday's rent is sunk - ignore it. ) 确定下一杯咖啡的 ** 边际成本(MC) **= $3 的额外投入。(昨天的租金是 ** 沉没成本(sunk) ** ––忽略它。) 3 Compare: MB $5 > MC $3 - brew it; net benefit rises by $2. 比较:MB $5>MC $3→煮它;净收益增加 $2。 4 Keep brewing until MB falls to meet MC. Stop where MB = MC - that is the profit-maximising quantity. 持续煮制,直到MB 下降至与 MC 相等 。** 在 MB= MC 处停止 **-- 那就是利润最大化的数量。 The same rule, with MB renamed marginal revenue, is exactly how the competitive firm picks output later in the course. 同样的法则,把 MB 改名为边际收益(MR),正是课程后面竞争性企业选择产量的方式。 ★ Exam move - the four-question checklist for any choice 考试技巧 -- 任何选择的四问清单 Faced with any decision problem, run: (1) What is scarce? (2) What is the opportunity cost of the chosen option - the next-best forgone, ignoring sunk costs? (3) Is this a marginal choice - compare MB to MC? (4) Is the claim positive or normative? Answer these four and you have the reasoning the rest of the subject builds on. 面对任何决策问题,跑一遍:(1)什么是稀缺的?(2)所选选项的机会成本是什么 -- 被放弃的次优选项,忽略沉没成 本?(3)这是边际选择吗 -- 比较 MB与 MC?(4)该论断是实证还是规范?答完这四个,你就有了整个学科赖以构建的 推理。 AskSia Library . ECB1101 · 双语 Bilingual CH 2 . TRADE WHY WE SPECIALISE - CHAPTER 2 Gains from trade 贸易的收益 Why even the more productive partner gains by specialising 为何连更高产的一方也能从专业化中获益 IN ONE LINE Trade is driven by comparative advantage (lower opportunity cost), not absolute advantage (more output). Each side specialises where its opportunity cost is lowest, trades, and both consume beyond their own PPF. 贸易由比较优势(comparative advantage)(机会成本更低)驱动,而非绝对优势(absolute advantage)(产量更多)。各方 都专于自己机会成本最低之处,进行贸易,双方的消费都能超出各自的PPF。 This is Week 2 (Mankiw Ch 3). A producer has an absolute advantage if it can make more of a good with the same resources. It has a comparative advantage if it can make the good at a lower opportunity cost. The headline result - the one the exam loves because it is counter-intuitive - is that specialisation is dictated by comparative, not absolute, advantage. 这是第2周(Mankiw 第3章)。一个生产者若能用相同资源生产更多某商品,便具有绝对优势(absolute advantage)。若能 以更低的机会成本(opportunity cost)生产某商品,便具有比较优势(comparative advantage)。最核心的结论 -- 考试钟爱 它,因为它违反直觉 -- 是专业化由比较优势而非绝对优势决定。 ★ How ECB1101 tests this ECB1101 如何考查这一点 Week 2 items hand you an output table for two producers and ask you to: compute each producer's opportunity cost of each good, identify who holds comparative advantage in what, and state the range of prices at which both gain from trade. It appears in Section A (MCQ "who should produce X?") and as a Section B/C calculation with a short written justification. 第2 周的题目给你两个生产者的产出表,要你:算出每个生产者对每种商品的机会成本,指认谁在何商品上握有比较优 势,并说出双方都能从贸易中获益的价格区间。它出现在A部分(MCQ“谁该生产X?”),也作为带简短书面论证的B/C 部分计算题。 2. 1 Absolute vs comparative advantage 2. 1 绝对优势 vs 比较优势 AskSia Library . ECB1101 · 双语 Bilingual
- Positive vs Normative（实证 vs 规范）：遇到“描述事实”还是“价值判断”的句子，要能判。[9]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdf一家咖啡馆每杯咖啡卖 $5。冲下一杯的边际成本(咖啡豆、牛奶、纸杯、咖啡师的一分钟)是 $3。它该不该再冲一杯? 1 Identify MB of the next coffee = the $5 it sells for. 确定下一杯咖啡的 ** 边际收益(MB) **= 其售价 $5。 2 Identify MC of the next coffee = the $3 of extra inputs. (Yesterday's rent is sunk - ignore it. ) 确定下一杯咖啡的 ** 边际成本(MC) **= $3 的额外投入。(昨天的租金是 ** 沉没成本(sunk) ** ––忽略它。) 3 Compare: MB $5 > MC $3 - brew it; net benefit rises by $2. 比较:MB $5>MC $3→煮它;净收益增加 $2。 4 Keep brewing until MB falls to meet MC. Stop where MB = MC - that is the profit-maximising quantity. 持续煮制,直到MB 下降至与 MC 相等 。** 在 MB= MC 处停止 **-- 那就是利润最大化的数量。 The same rule, with MB renamed marginal revenue, is exactly how the competitive firm picks output later in the course. 同样的法则,把 MB 改名为边际收益(MR),正是课程后面竞争性企业选择产量的方式。 ★ Exam move - the four-question checklist for any choice 考试技巧 -- 任何选择的四问清单 Faced with any decision problem, run: (1) What is scarce? (2) What is the opportunity cost of the chosen option - the next-best forgone, ignoring sunk costs? (3) Is this a marginal choice - compare MB to MC? (4) Is the claim positive or normative? Answer these four and you have the reasoning the rest of the subject builds on. 面对任何决策问题,跑一遍:(1)什么是稀缺的?(2)所选选项的机会成本是什么 -- 被放弃的次优选项,忽略沉没成 本?(3)这是边际选择吗 -- 比较 MB与 MC?(4)该论断是实证还是规范?答完这四个,你就有了整个学科赖以构建的 推理。 AskSia Library . ECB1101 · 双语 Bilingual CH 2 . TRADE WHY WE SPECIALISE - CHAPTER 2 Gains from trade 贸易的收益 Why even the more productive partner gains by specialising 为何连更高产的一方也能从专业化中获益 IN ONE LINE Trade is driven by comparative advantage (lower opportunity cost), not absolute advantage (more output). Each side specialises where its opportunity cost is lowest, trades, and both consume beyond their own PPF. 贸易由比较优势(comparative advantage)(机会成本更低)驱动,而非绝对优势(absolute advantage)(产量更多)。各方 都专于自己机会成本最低之处,进行贸易,双方的消费都能超出各自的PPF。 This is Week 2 (Mankiw Ch 3). A producer has an absolute advantage if it can make more of a good with the same resources. It has a comparative advantage if it can make the good at a lower opportunity cost. The headline result - the one the exam loves because it is counter-intuitive - is that specialisation is dictated by comparative, not absolute, advantage. 这是第2周(Mankiw 第3章)。一个生产者若能用相同资源生产更多某商品,便具有绝对优势(absolute advantage)。若能 以更低的机会成本(opportunity cost)生产某商品,便具有比较优势(comparative advantage)。最核心的结论 -- 考试钟爱 它,因为它违反直觉 -- 是专业化由比较优势而非绝对优势决定。 ★ How ECB1101 tests this ECB1101 如何考查这一点 Week 2 items hand you an output table for two producers and ask you to: compute each producer's opportunity cost of each good, identify who holds comparative advantage in what, and state the range of prices at which both gain from trade. It appears in Section A (MCQ "who should produce X?") and as a Section B/C calculation with a short written justification. 第2 周的题目给你两个生产者的产出表,要你:算出每个生产者对每种商品的机会成本,指认谁在何商品上握有比较优 势,并说出双方都能从贸易中获益的价格区间。它出现在A部分(MCQ“谁该生产X?”),也作为带简短书面论证的B/C 部分计算题。 2. 1 Absolute vs comparative advantage 2. 1 绝对优势 vs 比较优势 AskSia Library . ECB1101 · 双语 Bilingual[20]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdf★ How ECB1101 tests this ECB1101 如何考查这一点 Week 1 ideas surface as Section A multiple-choice and true/false concept checks: name the opportunity cost of a choice (ignoring sunk costs), read a point as efficient / inefficient / unattainable on a PPF, decide whether a statement is positive or normative, and apply the MB = MC rule. The recurring trap is confusing what you spent with what you gave up. 第1周的理念以 A 部分选择题和判断题概念检查出现:说出一个选择的机会成本(忽略沉没成本),把 PPF 上一个点读作 有效率/无效率/不可达,判断一句话是实证还是规范,并应用MB= MC 法则。反复出现的陷阱是把你花掉的与你放 弃的混为一谈。 1. 1 Scarcity & the economic problem 1. 1 稀缺与经济问题 Human wants are unlimited; the resources to satisfy them - time, labour, capital, land - are finite. That gap is scarcity, and it forces every individual, firm and society to choose. To choose one thing is, at the same instant, to choose not to do something else. Economics studies how scarce resources are allocated among competing uses, and the tool that values any choice is its opportunity cost. - 人的欲望无限;满足欲望的资源 -- 时间、劳动、资本、土地 -- 是有限的。这道缺口就是稀缺(scarcity),它迫使每个人、 每家企业和整个社会去选择。选择一件事,就在同一刻选择了不做另一件事。经济学研究稀缺资源如何在相互竞争的用途间配 置,而衡量任何选择的工具就是它的机会成本。 - 1. 2 Opportunity cost 1. 2 机会成本 AskSia Library · ECB1101 · 双语 Bilingual The opportunity cost of a choice is the value of the next-best alternative forgone - the single best thing you gave up to get what you chose. It is not the sum of everything you did not do, and it is not the dollar price on the tag. For students the biggest cost is usually time: the wage you could have earned, the study you could have done. 一个选择的机会成本(opportunity cost)是被放弃的次优选项的价值 -- 你为得到所选之物而放弃的那一件最好的东西。它不 是你没做的所有事之和,也不是标签上的金额。对学生而言最大的成本通常是时间:你本可赚到的工资、本可完成的学习。 DEFINITION opportunity cost = value of the next-best alternative forgone ! Sunk costs are not opportunity costs 沉没成本不是机会成本 A sunk cost is money already spent that cannot be recovered - a non-refundable ticket, last semester's fees. It is the same whatever you choose next, so it is irrelevant to the decision. Rational choice looks only forward: weigh the marginal benefit against the opportunity cost of the next action, and ignore what is already gone. 沉没成本(sunk cost)是已经花掉、无法收回的钱 -- 一张不可退的票、上学期的学费。无论你接下来怎么选它都一样, 所以它与决策无关。理性选择只向前看:权衡下一步行动的边际收益与机会成本,无视已经逝去的。 AskSia Library . ECB1101 · 双语 Bilingual CH 1 . PPF - CHAPTER 1 (CONT. ) The production possibility frontier 生产可能性边界 (PPF) Drawing scarcity, trade-offs and efficiency in one curve 用一条曲线画出稀缺、权衡与效率 1. 3 The PPF 1. 3 PPF The production possibility frontier (PPF) shows the maximum combinations of two goods an economy can produce when all resources are fully and efficiently used. It makes scarcity visible: to get more of one good you must move along the curve and give up some of the other - and that sacrifice is the opportunity cost. 生产可能性边界(PPF)展示了当所有资源被充分且有效利用 时,一个经济体能生产的两种商品的最大组合。它让稀缺可 见:要多生产一种商品,你必须沿着曲线移动、放弃一些另 一种 -- 而那份牺牲就是机会成本。 - On the curve - efficient (no waste; producing the most possible). 曲线 **** → ** 有效率 ** (无浪费;产出尽可能多)。
- PPF（生产可能性边界）：
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考试怎么考你（你要练什么）
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Week 2 / Chapter 2：贸易与比较优势（Section A + B/C 计算）
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核心结论（必须会用“机会成本”算）
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宝典明确的考法（非常具体）
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Week 3 / Chapter 3：供给与需求（B/C 的“发动机”）
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你要会的“最核心区分”（MCQ 经常用来下套）
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线性供需必会算法（B/C 最常见开头）
- 若给你 $Q_d = a-bP$ 与 $Q_s = c+dP$：
- 令 $Q_d = Q_s$ 解 $P^*$
- 再代回求 $Q^*$
- 并做“代回另一条方程检查”拿送分。[19]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfIf a shock moves both curves at once (e. g. a substitute enters and an input gets cheaper), only one of P* or Q* is determined - the other is ambiguous and depends on the relative size of the two shifts. Saying "ambiguous, because it depends on which shift dominates" with a reason earns the mark. 若一次冲击同时移动两条曲线(例如有替代品进入且某 投入变便宜),那么 P*或Q* 中只有一个确定 -- 另 一个不确定,取决于两次移动的相对大小。带理由地 说“不确定,因为取决于哪次移动占主导”就能得分。 AskSia Library . ECB1101 · 双语 Bilingual CH 3 . SOLVE - CHAPTER 3 (CONT. ) Solving linear demand & supply 求解线性需求与供给 The algebra the exam wants on paper, step by step 考试要在纸上写出的代数,一步步来 When demand and supply are given as linear equations, equilibrium is pure algebra: set quantity demanded equal to quantity supplied, solve for price, then substitute back for quantity. This is the most common open-response opener - show every line. 当需求与供给以线性方程给出时,均衡纯属代数:令需求量等于供给量,解出价格,再代回求数量。这是最常见的开放题开场 每一步都要写出来。 LINEAR D & S METHOD Given Q = a - bP and Qs = c + dP set Qa = Qs - solve for P* - sub back for Q* AskSia Library . ECB1101 · 双语 Bilingual EX 3. 1 Equilibrium from linear equations W3 . CONFIRMED A market has demand and supply (price P in dollars): 某市场的需求与供给(价格 P 以美元计): GIVEN Qa = 120 - 4P Qs = 6P 1 Set Qd = Qs. 120 - 4P = 6P ** 令 Qd=Qso ** 120 - 4P= 6P 2 Collect the P terms. 120 = 6P + 4P = 10P ** 归并 P 项 。** 120 = 6P + 4P = 10P 3 Solve for price. P* = 120 + 10 = $12 ** 解出价格 。** P* = 120 ÷ 10 = ** $12 ** 4 Substitute back for quantity. Q* = 6P* = 6 x 12 = 72 (check: 120 - 4x12 = 72 V) ** 回代求数量 。** Q *= 6P *= 6×12 =** 72 ** (验 证:120-4×12=72√) -[10]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfEquilibrium: P* = $12, Q* = 72. The check - sub P* into the other curve and confirm the same Q - is free marks. 均衡:P *= $12, Q *= 72。检验––把 P*代入另一 条曲线、确认得到相同的 Q -- 是白送的分。 - Price ($) S $12 D Quantity The worked market: Qd=120-4P and Qs=6P cross at P *= $12, Q *= 72. The same picture underlies every later surplus, tax and welfare calculation. 已解市场:Qd=120-4P 与 Qs=6P 相交于 P *= $12, Q *= 72。后续所有剩余、税收和福利计算都以这张图为 基础。 i Reading the equations as a picture 把方程读成一幅图 Qd=120-4P hits the price axis at P=$30 (where Q=0) and the quantity axis at Q=120 (where P=0). Qs=6P starts at the origin. Sketching those intercepts before solving catches sign errors fast. Qd=120-4P 在 P=$30 处(Q=0)碰到价格轴,在 Q=120 处(P=0)碰到数量轴。Qs=6P 从原点出发。求 解前先草绘这些截距能快速抓出符号错误。 ! Demand vs quantity demanded; P-on-axis confusion 需求 vs 需求量;P 在纵轴的混淆 Two recurring slips: (1) Although we write Q as a function of P, economists draw P on the vertical axis - do the algebra in whichever form is given, then map to the graph. (2) Set quantities equal, never prices - demand and supply share the same market price, so it is Qd = Qs that pins down P *. 两个反复出现的失误:(1)虽然我们把 Q 写成 P的函数,但经济学家把 P 画在纵轴 -- 用给定的形式做代数,再映射到 图上。(2)令数量相等,绝不令价格相等 -- 供求共享同一个市场价格,所以是 Qd= Qs 钉住 P *。 AskSia Library . ECB1101 · 双语 Bilingual ★ Exam move - the equilibrium-first habit 考试技巧 -- 先求均衡的习惯 Whatever the policy to come - tax, subsidy, floor, ceiling - the first marks are always the free-market equilibrium: set Qd=Qs, get (P*, Q*), and label it on a clean, fully-labelled diagram (both axes, both curves, the crossing point). Everything in Weeks 4-6 is measured as a change from this point. 无论接下来是什么政策 -- 税、补贴、价格下限、价格上限 -- 头几分总是自由市场均衡:令 Qd=Qs,得(P*,Q*),并 在一张干净、完整标注的图上把它标出来(两条轴、两条曲线、交点)。第4-6周的一切都以从这一点起的变化来衡量。 AskSia Library . ECB1101 · 双语 Bilingual CH 4 . MIDPOINT PED - CHAPTER 4 . ELASTICITY THE CALC-HEAVY WEEK How much quantity responds - as a number 数量反应有多大 -- 用数字说话 Price, income and cross-price elasticity by the midpoint method 用中点法求价格、收入与交叉价格弹性 IN ONE LINE Elasticity turns a curve's slope into a unit-free number. ECB1101 computes it by the midpoint (arc) method: %AQ and %AP are each change * average, so the same number comes out whichever direction you move. |E| > 1 elastic, < 1 inelastic, = 1 unit-elastic. 弹性把曲线的斜率变成一个无单位的数字。ECB1101 用中点(弧)法(midpoint method)计算:%△Q 和 %△P 各为变化量 ÷ 平均值,所以无论朝哪个方向移动都得出同一个数。|||>1富有弹性,<1缺乏弹性,=1单位弹性。
- 重要提醒：
- 经济学图里 $P$ 在纵轴（别把坐标弄反）[10]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfEquilibrium: P* = $12, Q* = 72. The check - sub P* into the other curve and confirm the same Q - is free marks. 均衡:P *= $12, Q *= 72。检验––把 P*代入另一 条曲线、确认得到相同的 Q -- 是白送的分。 - Price ($) S $12 D Quantity The worked market: Qd=120-4P and Qs=6P cross at P *= $12, Q *= 72. The same picture underlies every later surplus, tax and welfare calculation. 已解市场:Qd=120-4P 与 Qs=6P 相交于 P *= $12, Q *= 72。后续所有剩余、税收和福利计算都以这张图为 基础。 i Reading the equations as a picture 把方程读成一幅图 Qd=120-4P hits the price axis at P=$30 (where Q=0) and the quantity axis at Q=120 (where P=0). Qs=6P starts at the origin. Sketching those intercepts before solving catches sign errors fast. Qd=120-4P 在 P=$30 处(Q=0)碰到价格轴,在 Q=120 处(P=0)碰到数量轴。Qs=6P 从原点出发。求 解前先草绘这些截距能快速抓出符号错误。 ! Demand vs quantity demanded; P-on-axis confusion 需求 vs 需求量;P 在纵轴的混淆 Two recurring slips: (1) Although we write Q as a function of P, economists draw P on the vertical axis - do the algebra in whichever form is given, then map to the graph. (2) Set quantities equal, never prices - demand and supply share the same market price, so it is Qd = Qs that pins down P *. 两个反复出现的失误:(1)虽然我们把 Q 写成 P的函数,但经济学家把 P 画在纵轴 -- 用给定的形式做代数,再映射到 图上。(2)令数量相等,绝不令价格相等 -- 供求共享同一个市场价格,所以是 Qd= Qs 钉住 P *。 AskSia Library . ECB1101 · 双语 Bilingual ★ Exam move - the equilibrium-first habit 考试技巧 -- 先求均衡的习惯 Whatever the policy to come - tax, subsidy, floor, ceiling - the first marks are always the free-market equilibrium: set Qd=Qs, get (P*, Q*), and label it on a clean, fully-labelled diagram (both axes, both curves, the crossing point). Everything in Weeks 4-6 is measured as a change from this point. 无论接下来是什么政策 -- 税、补贴、价格下限、价格上限 -- 头几分总是自由市场均衡:令 Qd=Qs,得(P*,Q*),并 在一张干净、完整标注的图上把它标出来(两条轴、两条曲线、交点)。第4-6周的一切都以从这一点起的变化来衡量。 AskSia Library . ECB1101 · 双语 Bilingual CH 4 . MIDPOINT PED - CHAPTER 4 . ELASTICITY THE CALC-HEAVY WEEK How much quantity responds - as a number 数量反应有多大 -- 用数字说话 Price, income and cross-price elasticity by the midpoint method 用中点法求价格、收入与交叉价格弹性 IN ONE LINE Elasticity turns a curve's slope into a unit-free number. ECB1101 computes it by the midpoint (arc) method: %AQ and %AP are each change * average, so the same number comes out whichever direction you move. |E| > 1 elastic, < 1 inelastic, = 1 unit-elastic. 弹性把曲线的斜率变成一个无单位的数字。ECB1101 用中点(弧)法(midpoint method)计算:%△Q 和 %△P 各为变化量 ÷ 平均值,所以无论朝哪个方向移动都得出同一个数。|||>1富有弹性,<1缺乏弹性,=1单位弹性。
- 永远令数量相等，不要令价格相等（均衡由 $Q_d=Q_s$ 钉住）。[10]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfEquilibrium: P* = $12, Q* = 72. The check - sub P* into the other curve and confirm the same Q - is free marks. 均衡:P *= $12, Q *= 72。检验––把 P*代入另一 条曲线、确认得到相同的 Q -- 是白送的分。 - Price ($) S $12 D Quantity The worked market: Qd=120-4P and Qs=6P cross at P *= $12, Q *= 72. The same picture underlies every later surplus, tax and welfare calculation. 已解市场:Qd=120-4P 与 Qs=6P 相交于 P *= $12, Q *= 72。后续所有剩余、税收和福利计算都以这张图为 基础。 i Reading the equations as a picture 把方程读成一幅图 Qd=120-4P hits the price axis at P=$30 (where Q=0) and the quantity axis at Q=120 (where P=0). Qs=6P starts at the origin. Sketching those intercepts before solving catches sign errors fast. Qd=120-4P 在 P=$30 处(Q=0)碰到价格轴,在 Q=120 处(P=0)碰到数量轴。Qs=6P 从原点出发。求 解前先草绘这些截距能快速抓出符号错误。 ! Demand vs quantity demanded; P-on-axis confusion 需求 vs 需求量;P 在纵轴的混淆 Two recurring slips: (1) Although we write Q as a function of P, economists draw P on the vertical axis - do the algebra in whichever form is given, then map to the graph. (2) Set quantities equal, never prices - demand and supply share the same market price, so it is Qd = Qs that pins down P *. 两个反复出现的失误:(1)虽然我们把 Q 写成 P的函数,但经济学家把 P 画在纵轴 -- 用给定的形式做代数,再映射到 图上。(2)令数量相等,绝不令价格相等 -- 供求共享同一个市场价格,所以是 Qd= Qs 钉住 P *。 AskSia Library . ECB1101 · 双语 Bilingual ★ Exam move - the equilibrium-first habit 考试技巧 -- 先求均衡的习惯 Whatever the policy to come - tax, subsidy, floor, ceiling - the first marks are always the free-market equilibrium: set Qd=Qs, get (P*, Q*), and label it on a clean, fully-labelled diagram (both axes, both curves, the crossing point). Everything in Weeks 4-6 is measured as a change from this point. 无论接下来是什么政策 -- 税、补贴、价格下限、价格上限 -- 头几分总是自由市场均衡:令 Qd=Qs,得(P*,Q*),并 在一张干净、完整标注的图上把它标出来(两条轴、两条曲线、交点)。第4-6周的一切都以从这一点起的变化来衡量。 AskSia Library . ECB1101 · 双语 Bilingual CH 4 . MIDPOINT PED - CHAPTER 4 . ELASTICITY THE CALC-HEAVY WEEK How much quantity responds - as a number 数量反应有多大 -- 用数字说话 Price, income and cross-price elasticity by the midpoint method 用中点法求价格、收入与交叉价格弹性 IN ONE LINE Elasticity turns a curve's slope into a unit-free number. ECB1101 computes it by the midpoint (arc) method: %AQ and %AP are each change * average, so the same number comes out whichever direction you move. |E| > 1 elastic, < 1 inelastic, = 1 unit-elastic. 弹性把曲线的斜率变成一个无单位的数字。ECB1101 用中点(弧)法(midpoint method)计算:%△Q 和 %△P 各为变化量 ÷ 平均值,所以无论朝哪个方向移动都得出同一个数。|||>1富有弹性,<1缺乏弹性,=1单位弹性。
- 若给你 $Q_d = a-bP$ 与 $Q_s = c+dP$：
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比较静态（Comparative statics）必考点
- 给你一次 shift，问 $P^*$、$Q^*$ 怎么变。[13]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdf市场(market)在需求量等于供给量的价格处达成均衡。商品的自身价格使你沿着曲线移动;其他任何因素都会使整条曲 线移动。钉牢这一区分和四种移动情形,你就掌握了 ECB1101。 This is Week 3 (Mankiw Ch 4). A market is buyers and sellers of a good interacting. Demand and supply is the engine of the whole subject: nearly every exam calculation begins by finding where the two curves cross, then layers a policy on top. Get the two curves, the difference between a shift and a movement, and the four comparative-static cases - and you own the model. 这是第 3周(Mankiw 第4章)。市场(market)是某商品的买方与卖方在互动。供给与需求是整个学科的引擎:几乎每道考试计 算都从找两条曲线的交点开始,再在其上叠加一项政策。掌握这两条曲线、移动(shift)与滑动(movement)的区别,以及四种 比较静态情形 -- 你就掌握了这个模型。 ★ How ECB1101 tests this ECB1101 如何考查这一点 Week 3 is the workhorse of Sections B and C. Expect: read a P-Q schedule and find (P*, Q*); classify a change as a movement along vs a shift of a curve; run comparative statics (given a shift, say what happens to P* and Q* - including the "ambiguous" case when both curves move); and solve linear D & S algebraically. Section C wants the diagram drawn and every shift arrowed. 第3 周是B、C 两部分的主力。预期会有:读 P-Q 表并求(P*,Q*);把一项变化归类为曲线的沿线滑动还是移动;做 比较静态(给定一次移动,说出 P*和Q*会怎样 -- 包括两条曲线都动时的“不确定”情形);以及对线性供求做代数求 解。C部分要求画出图并给每次移动加箭头。 AskSia Library . ECB1101 · 双语 Bilingual 3. 1 The demand curve 3. 1 需求曲线 The law of demand: holding all else equal, as a good's price rises, the quantity demanded falls. Demand therefore slopes downward. Read it two ways - at each price, how much buyers want; and for each quantity, the most a buyer will pay (their marginal value). 需求定律:其他条件不变时,某商品价格上升,其需求量下 降。因此需求曲线向下倾斜。可两种读法 -- 在每个价格上 买方想要多少;以及对每个数量,买方愿付的最高价(他们 的边际价值)。 Demand shifters (the whole curve moves) 需求移动因素(整条曲线移动) - Income - a normal good: more income shifts D right; an inferior good: more income shifts D left. ** 收入 **--* 正常品 *: 收入增加使 D右移 ;* 劣等品 *: 收入增加使 D 左移。 → Prices of related goods - substitutes & complements. ** 相关商品价格 **-- 替代品与互补品。 - Tastes / preferences. ** 口味 ** /偏好。 - Expectations of future price or income. | 对未来价格或收入的 ** 预期 **。 → Number of buyers in the market. 市场中的 ** 买方数量 **。 3. 2 The supply curve 3. 2 供给曲线 The law of supply: holding all else equal, as price rises, the quantity supplied rises - higher prices make production worthwhile. Supply slopes upward; read each point as the lowest price a seller will accept (their marginal cost). 供给定律:其他条件不变时,价格上升,供给量上升 -- 更 高的价格使生产更值得。供给曲线向上倾斜;每个点读作卖 方愿意接受的最低价(他们的边际成本)。 Supply shifters (the whole curve moves) 供给移动因素(整条曲线移动) - Input (factor) prices - cheaper inputs shift S right. ** 投入品(要素)价格 **-- 投入品变便宜使 S 右移。 Price ($) S
- 若一次冲击 两条曲线同时移动：通常 一个确定、另一个“不确定/取决于哪边移动更大”；你写出“ambiguous + 取决于相对大小”的理由就能得分。[19]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfIf a shock moves both curves at once (e. g. a substitute enters and an input gets cheaper), only one of P* or Q* is determined - the other is ambiguous and depends on the relative size of the two shifts. Saying "ambiguous, because it depends on which shift dominates" with a reason earns the mark. 若一次冲击同时移动两条曲线(例如有替代品进入且某 投入变便宜),那么 P*或Q* 中只有一个确定 -- 另 一个不确定,取决于两次移动的相对大小。带理由地 说“不确定,因为取决于哪次移动占主导”就能得分。 AskSia Library . ECB1101 · 双语 Bilingual CH 3 . SOLVE - CHAPTER 3 (CONT. ) Solving linear demand & supply 求解线性需求与供给 The algebra the exam wants on paper, step by step 考试要在纸上写出的代数,一步步来 When demand and supply are given as linear equations, equilibrium is pure algebra: set quantity demanded equal to quantity supplied, solve for price, then substitute back for quantity. This is the most common open-response opener - show every line. 当需求与供给以线性方程给出时,均衡纯属代数:令需求量等于供给量,解出价格,再代回求数量。这是最常见的开放题开场 每一步都要写出来。 LINEAR D & S METHOD Given Q = a - bP and Qs = c + dP set Qa = Qs - solve for P* - sub back for Q* AskSia Library . ECB1101 · 双语 Bilingual EX 3. 1 Equilibrium from linear equations W3 . CONFIRMED A market has demand and supply (price P in dollars): 某市场的需求与供给(价格 P 以美元计): GIVEN Qa = 120 - 4P Qs = 6P 1 Set Qd = Qs. 120 - 4P = 6P ** 令 Qd=Qso ** 120 - 4P= 6P 2 Collect the P terms. 120 = 6P + 4P = 10P ** 归并 P 项 。** 120 = 6P + 4P = 10P 3 Solve for price. P* = 120 + 10 = $12 ** 解出价格 。** P* = 120 ÷ 10 = ** $12 ** 4 Substitute back for quantity. Q* = 6P* = 6 x 12 = 72 (check: 120 - 4x12 = 72 V) ** 回代求数量 。** Q *= 6P *= 6×12 =** 72 ** (验 证:120-4×12=72√) -
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Week 4 / Chapter 4：弹性 Elasticity（计算量最大周，Quiz 1 核心）
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必背：中点法（arc / midpoint）公式（ECB1101 默认用它）
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三个区间（选择题喜欢问分类）
- $|PED|>1$：Elastic（富有弹性）[16]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfA demand curve tells you that quantity falls when price rises. Elasticity answers the next question - by how much? It converts a slope into a single, unit-free figure you can compute, compare across goods and tie directly to revenue. This is the most calculation-heavy week of the unit, and the engine of Quiz 1. 需求曲线告诉你价格上升时数量会下降。弹性(elasticity)回答下一个问题 -- 下降多少?它把斜率转化为一个可计算、可跨商 品比较、并直接与收益挂钩的无单位数字。这是本课程计算量最大的一周,也是测验1(Quiz 1)的引擎。 ★ What the exam asks here 这里考试问什么 Compute price elasticity of demand from a two-row schedule by the midpoint method; classify it as elastic / inelastic / unit-elastic; apply the total-revenue rule to say which way to move price; and read off income and cross-price elasticities by their sign. Quiz 1 (Week 5) is built almost entirely from this chapter - MCQ + a calculation + a graph. Answers are usually clean numbers and a calculator is allowed, so show every step. 用中点法从两行表算需求价格弹性;把它归类为富有弹性/缺乏弹性/单位弹性;应用总收益法则说出价格该往哪动; 并按符号读出收入和交叉价格弹性。测验1(第5周)几乎全部由本章构成 -- MCQ+一道计算+一张图。答案通常是干 净的数字且允许用计算器,所以每一步都要写出来。 4. 1 Price elasticity of demand - the midpoint method 4. 1 需求价格弹性(PED) –––中点法 The price elasticity of demand (PED) is the percentage change in quantity demanded divided by the percentage change in price. ECB1101 computes both percentages by the midpoint (arc) method: each change is divided by the average of the two values, not the starting value. 需求价格弹性(PED)是需求量的百分比变化除以价格的百分比变化。ECB1101 用中点(弧)法(midpoint method)算这两个百分 比:每个变化都除以两值的平均,而非起始值。 MIDPOINT (ARC) ELASTICITY PED where %4Q = (Q2-Q1) + [(Q1+Q2)/2] %AP %AP = (P2-P1) + [(P1+P2) /2] Because demand slopes down, %4Q and %AP have opposite signs, so PED is negative. The course classifies on the absolute value |PED|. AskSia Library · ECB1101 · 双语 Bilingual 由于需求向下倾斜,%△Q和%△P 符号相反,所以 PED 为负。课程按绝对值 |PED|来分类。 § Why ECB1101 uses the midpoint, not the point, formula ECB1101 为何用中点法而非点弹性公式 The midpoint method divides each change by the average of the start and end values. Its one virtue is direction- independence: the elasticity from $8-$10 equals the elasticity from $10-$8, because both use the same midpoint as the base. A plain %-change formula would give two different answers depending on which price you start from. This is the method the Workshop solutions and Quiz 1 use - match it exactly. 中点法把每个变化除以起止值的平均。它唯一的优点是方向无关:$8→$10 的弹性等于 $10→$8 的弹性,因为两者都以 同一个中点为基。普通的百分比变化公式会因你从哪个价格起算而给出两个不同答案。这是习题课答案和测验1所用的 方法 -- 精确匹配它。 The three regions 三个区域 | PED | Name Meaning > 1 Elastic Q responds more than proportionally to price = 1 Unit-elastic Q changes in the same proportion as price
- $|PED|<1$：Inelastic（缺乏弹性）[4]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfi 4 . A corrective tax = the external effect 4 · 矫正税 = 外部效应 A negative externality means SMC > PMC: the market over-produces. The fix is a Pigouvian tax = the marginal external cost (SMC - PMC, not the price gap), which lifts private cost to social cost and restores the efficient Q. Positive externality - subsidy = external benefit. Public good = non-rival + non- excludable - free-riding. ** 负外部性(negative externality) ** 意味着 ** SMC > PMC **: 市场 ** 生产过多 **。 对策是 ** 庇古税 (Pigouvian tax)= 边际外部成本 ** (SMC - PMC,* 不是*价格差),它把私人成本抬升至社会成本,恢复 有效的Q。正外部性→补贴=外部收益。公共物品 = 非竞争性+非排他性→搭便车(free-riding)。 AskSia Library . ECB1101 · 双语 Bilingual ✓ 2 . Elasticity by the midpoint method 2 . 用中点法(midpoint method)算弹性 ECB1101's default is the midpoint (arc) method: divide each %-change by the average of the two values. If demand is inelastic (|E| < 1), raise price to raise revenue; if elastic, cut it; TR peaks at |E| = 1. On a tax, the less-elastic side bears more - it cannot walk away. ECB1101 默认用 ** 中点法(arc method) **: 每个百分 比变化除以两值的 ** 平均 **。 若需求 ** 缺乏弹性 ** ([E]<1), ** 提价 ** 可增收入;若 ** 富有弹性 ** ,则 降价;TR在 | == 1时达到峰值。对于税收, ** 弹性 较小的一方承担更多 **-- 它无处可逃。 § 3 . P = MC competition / MR = MC monopoly 3 . 完全竞争 P = MC / 垄断 MR = MC A price taker has P = MR, so produces where P = MC; shut down if P < AVC; long run, free entry drives P to min ATC and profit to zero. A monopolist sets MR = MC for the quantity, then reads price off demand (MR = a - 2bQ, twice the slope). Because P > MC it under- produces - deadweight loss. ** 价格接受者(price taker) ** P = MR,故在 ** P = MC ** 处生产 ;** P <AVC 则停业(shut down) **; 长 期下自由进入将 P 压到 ** min ATC **、 利润压到 ** 零 **。** 垄断者(monopolist) ** 令 ** MR = MC ** 定数 量,再从 ** 需求曲线 ** 读出价格 (MR = a-2bQ,斜 率两倍)。因P>MC 而生产不足→无谓损失。 ✓ 5 . The four market structures at a glance 5 · 四种市场结构一览 Perfect competition: many firms, identical good, no barriers, P = MR = MC, zero LR profit. Monopolistic competition: many, differentiated, P > MC, excess capacity, zero LR profit (P = ATC tangency). Oligopoly: few firms, interdependent, market power. Monopoly: one firm, barriers, P > MR = MC, DWL. Markup (P - MC) > 0 for the last three. ** 完全竞争 **: 企业众多、产品同质、无壁垒,P= MR = MC,长期零利润 。** 垄断竞争 **: 众多、差异 化,P> MC,过剩产能,长期零利润(P=ATC相 切) 。** 寡头(oligopoly) **: 少数企业、相互依存、有 市场势力 。** 垄断 **: 单一企业、有壁垒,P> MR = MC,有 DWL。后三者加成(P-MC)>0。 ★ 6 . ALWAYS draw and fully label every Section-C graph 6 · C 部分每张图都要画出并完整标注 Axes named, both curves drawn, equilibrium marked, shifts shown with arrows, and CS / PS / DWL shaded and labelled. ECB1101 deducts marks for unlabelled axes, curves and movements - these are the easiest marks in the paper and an arithmetic slip cannot cost them. Draw the diagram even when the question does not explicitly ask. 坐标轴要命名, ** 两条曲线 ** 都画出,标出 ** 均衡点 ** , ** 用箭头表示移位 ** ,CS / PS / DWL ** 阴影并 标注 **。 ECB1101 ** 对未标注的坐标轴、曲线和移动 扣分 **-- 这些是全卷最易得的分,算术失误也夺不 走它们。即便题目没明说,也要画图。 ~1. 3 min PER MARK - PACE IT 每分 -- 把握节奏 130 min FOR 100 MARKS 对应 100 分 40 mk SECTION C - LEAVE TIME TO DRAW C 部分 -- 留时间画图 HURDLE - JUST BANK THE MARKS 门槛 -- 把分收下即可 ! Pace it: 100 marks in 130 minutes 把握节奏:130 分钟拿 100 分[16]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfA demand curve tells you that quantity falls when price rises. Elasticity answers the next question - by how much? It converts a slope into a single, unit-free figure you can compute, compare across goods and tie directly to revenue. This is the most calculation-heavy week of the unit, and the engine of Quiz 1. 需求曲线告诉你价格上升时数量会下降。弹性(elasticity)回答下一个问题 -- 下降多少?它把斜率转化为一个可计算、可跨商 品比较、并直接与收益挂钩的无单位数字。这是本课程计算量最大的一周,也是测验1(Quiz 1)的引擎。 ★ What the exam asks here 这里考试问什么 Compute price elasticity of demand from a two-row schedule by the midpoint method; classify it as elastic / inelastic / unit-elastic; apply the total-revenue rule to say which way to move price; and read off income and cross-price elasticities by their sign. Quiz 1 (Week 5) is built almost entirely from this chapter - MCQ + a calculation + a graph. Answers are usually clean numbers and a calculator is allowed, so show every step. 用中点法从两行表算需求价格弹性;把它归类为富有弹性/缺乏弹性/单位弹性;应用总收益法则说出价格该往哪动; 并按符号读出收入和交叉价格弹性。测验1(第5周)几乎全部由本章构成 -- MCQ+一道计算+一张图。答案通常是干 净的数字且允许用计算器,所以每一步都要写出来。 4. 1 Price elasticity of demand - the midpoint method 4. 1 需求价格弹性(PED) –––中点法 The price elasticity of demand (PED) is the percentage change in quantity demanded divided by the percentage change in price. ECB1101 computes both percentages by the midpoint (arc) method: each change is divided by the average of the two values, not the starting value. 需求价格弹性(PED)是需求量的百分比变化除以价格的百分比变化。ECB1101 用中点(弧)法(midpoint method)算这两个百分 比:每个变化都除以两值的平均,而非起始值。 MIDPOINT (ARC) ELASTICITY PED where %4Q = (Q2-Q1) + [(Q1+Q2)/2] %AP %AP = (P2-P1) + [(P1+P2) /2] Because demand slopes down, %4Q and %AP have opposite signs, so PED is negative. The course classifies on the absolute value |PED|. AskSia Library · ECB1101 · 双语 Bilingual 由于需求向下倾斜,%△Q和%△P 符号相反,所以 PED 为负。课程按绝对值 |PED|来分类。 § Why ECB1101 uses the midpoint, not the point, formula ECB1101 为何用中点法而非点弹性公式 The midpoint method divides each change by the average of the start and end values. Its one virtue is direction- independence: the elasticity from $8-$10 equals the elasticity from $10-$8, because both use the same midpoint as the base. A plain %-change formula would give two different answers depending on which price you start from. This is the method the Workshop solutions and Quiz 1 use - match it exactly. 中点法把每个变化除以起止值的平均。它唯一的优点是方向无关:$8→$10 的弹性等于 $10→$8 的弹性,因为两者都以 同一个中点为基。普通的百分比变化公式会因你从哪个价格起算而给出两个不同答案。这是习题课答案和测验1所用的 方法 -- 精确匹配它。 The three regions 三个区域 | PED | Name Meaning > 1 Elastic Q responds more than proportionally to price = 1 Unit-elastic Q changes in the same proportion as price
- $|PED|=1$：Unit-elastic（单位弹性）[16]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfA demand curve tells you that quantity falls when price rises. Elasticity answers the next question - by how much? It converts a slope into a single, unit-free figure you can compute, compare across goods and tie directly to revenue. This is the most calculation-heavy week of the unit, and the engine of Quiz 1. 需求曲线告诉你价格上升时数量会下降。弹性(elasticity)回答下一个问题 -- 下降多少?它把斜率转化为一个可计算、可跨商 品比较、并直接与收益挂钩的无单位数字。这是本课程计算量最大的一周,也是测验1(Quiz 1)的引擎。 ★ What the exam asks here 这里考试问什么 Compute price elasticity of demand from a two-row schedule by the midpoint method; classify it as elastic / inelastic / unit-elastic; apply the total-revenue rule to say which way to move price; and read off income and cross-price elasticities by their sign. Quiz 1 (Week 5) is built almost entirely from this chapter - MCQ + a calculation + a graph. Answers are usually clean numbers and a calculator is allowed, so show every step. 用中点法从两行表算需求价格弹性;把它归类为富有弹性/缺乏弹性/单位弹性;应用总收益法则说出价格该往哪动; 并按符号读出收入和交叉价格弹性。测验1(第5周)几乎全部由本章构成 -- MCQ+一道计算+一张图。答案通常是干 净的数字且允许用计算器,所以每一步都要写出来。 4. 1 Price elasticity of demand - the midpoint method 4. 1 需求价格弹性(PED) –––中点法 The price elasticity of demand (PED) is the percentage change in quantity demanded divided by the percentage change in price. ECB1101 computes both percentages by the midpoint (arc) method: each change is divided by the average of the two values, not the starting value. 需求价格弹性(PED)是需求量的百分比变化除以价格的百分比变化。ECB1101 用中点(弧)法(midpoint method)算这两个百分 比:每个变化都除以两值的平均,而非起始值。 MIDPOINT (ARC) ELASTICITY PED where %4Q = (Q2-Q1) + [(Q1+Q2)/2] %AP %AP = (P2-P1) + [(P1+P2) /2] Because demand slopes down, %4Q and %AP have opposite signs, so PED is negative. The course classifies on the absolute value |PED|. AskSia Library · ECB1101 · 双语 Bilingual 由于需求向下倾斜,%△Q和%△P 符号相反,所以 PED 为负。课程按绝对值 |PED|来分类。 § Why ECB1101 uses the midpoint, not the point, formula ECB1101 为何用中点法而非点弹性公式 The midpoint method divides each change by the average of the start and end values. Its one virtue is direction- independence: the elasticity from $8-$10 equals the elasticity from $10-$8, because both use the same midpoint as the base. A plain %-change formula would give two different answers depending on which price you start from. This is the method the Workshop solutions and Quiz 1 use - match it exactly. 中点法把每个变化除以起止值的平均。它唯一的优点是方向无关:$8→$10 的弹性等于 $10→$8 的弹性,因为两者都以 同一个中点为基。普通的百分比变化公式会因你从哪个价格起算而给出两个不同答案。这是习题课答案和测验1所用的 方法 -- 精确匹配它。 The three regions 三个区域 | PED | Name Meaning > 1 Elastic Q responds more than proportionally to price = 1 Unit-elastic Q changes in the same proportion as price
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Total Revenue Rule（总收益法则，必背）
- 若需求缺乏弹性 $|PED|<1$：提价 → TR 上升
- 若需求富有弹性 $|PED|>1$：提价 → TR 下降
- 若 $|PED|=1$：TR 不变（且处于峰值）。[4]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfi 4 . A corrective tax = the external effect 4 · 矫正税 = 外部效应 A negative externality means SMC > PMC: the market over-produces. The fix is a Pigouvian tax = the marginal external cost (SMC - PMC, not the price gap), which lifts private cost to social cost and restores the efficient Q. Positive externality - subsidy = external benefit. Public good = non-rival + non- excludable - free-riding. ** 负外部性(negative externality) ** 意味着 ** SMC > PMC **: 市场 ** 生产过多 **。 对策是 ** 庇古税 (Pigouvian tax)= 边际外部成本 ** (SMC - PMC,* 不是*价格差),它把私人成本抬升至社会成本,恢复 有效的Q。正外部性→补贴=外部收益。公共物品 = 非竞争性+非排他性→搭便车(free-riding)。 AskSia Library . ECB1101 · 双语 Bilingual ✓ 2 . Elasticity by the midpoint method 2 . 用中点法(midpoint method)算弹性 ECB1101's default is the midpoint (arc) method: divide each %-change by the average of the two values. If demand is inelastic (|E| < 1), raise price to raise revenue; if elastic, cut it; TR peaks at |E| = 1. On a tax, the less-elastic side bears more - it cannot walk away. ECB1101 默认用 ** 中点法(arc method) **: 每个百分 比变化除以两值的 ** 平均 **。 若需求 ** 缺乏弹性 ** ([E]<1), ** 提价 ** 可增收入;若 ** 富有弹性 ** ,则 降价;TR在 | == 1时达到峰值。对于税收, ** 弹性 较小的一方承担更多 **-- 它无处可逃。 § 3 . P = MC competition / MR = MC monopoly 3 . 完全竞争 P = MC / 垄断 MR = MC A price taker has P = MR, so produces where P = MC; shut down if P < AVC; long run, free entry drives P to min ATC and profit to zero. A monopolist sets MR = MC for the quantity, then reads price off demand (MR = a - 2bQ, twice the slope). Because P > MC it under- produces - deadweight loss. ** 价格接受者(price taker) ** P = MR,故在 ** P = MC ** 处生产 ;** P <AVC 则停业(shut down) **; 长 期下自由进入将 P 压到 ** min ATC **、 利润压到 ** 零 **。** 垄断者(monopolist) ** 令 ** MR = MC ** 定数 量,再从 ** 需求曲线 ** 读出价格 (MR = a-2bQ,斜 率两倍)。因P>MC 而生产不足→无谓损失。 ✓ 5 . The four market structures at a glance 5 · 四种市场结构一览 Perfect competition: many firms, identical good, no barriers, P = MR = MC, zero LR profit. Monopolistic competition: many, differentiated, P > MC, excess capacity, zero LR profit (P = ATC tangency). Oligopoly: few firms, interdependent, market power. Monopoly: one firm, barriers, P > MR = MC, DWL. Markup (P - MC) > 0 for the last three. ** 完全竞争 **: 企业众多、产品同质、无壁垒,P= MR = MC,长期零利润 。** 垄断竞争 **: 众多、差异 化,P> MC,过剩产能,长期零利润(P=ATC相 切) 。** 寡头(oligopoly) **: 少数企业、相互依存、有 市场势力 。** 垄断 **: 单一企业、有壁垒,P> MR = MC,有 DWL。后三者加成(P-MC)>0。 ★ 6 . ALWAYS draw and fully label every Section-C graph 6 · C 部分每张图都要画出并完整标注 Axes named, both curves drawn, equilibrium marked, shifts shown with arrows, and CS / PS / DWL shaded and labelled. ECB1101 deducts marks for unlabelled axes, curves and movements - these are the easiest marks in the paper and an arithmetic slip cannot cost them. Draw the diagram even when the question does not explicitly ask. 坐标轴要命名, ** 两条曲线 ** 都画出,标出 ** 均衡点 ** , ** 用箭头表示移位 ** ,CS / PS / DWL ** 阴影并 标注 **。 ECB1101 ** 对未标注的坐标轴、曲线和移动 扣分 **-- 这些是全卷最易得的分,算术失误也夺不 走它们。即便题目没明说,也要画图。 ~1. 3 min PER MARK - PACE IT 每分 -- 把握节奏 130 min FOR 100 MARKS 对应 100 分 40 mk SECTION C - LEAVE TIME TO DRAW C 部分 -- 留时间画图 HURDLE - JUST BANK THE MARKS 门槛 -- 把分收下即可 ! Pace it: 100 marks in 130 minutes 把握节奏:130 分钟拿 100 分[18]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfTOTAL - REVENUE RULE Inelastic (|PED | <1): raise P - TR rises Elastic (| PED | >1): raise P - TR Falls Unit-elastic (|PED |=1): TR is unchanged (at its max) AskSia Library · ECB1101 · 双语 Bilingual ** 市场界定 **-- 狭义市场(单一品牌)比广义市场(所有 食品)更富有弹性。 ✓ Exam move - which way to move price 考试技巧 -- 价格该往哪个方向动 To raise revenue, push price toward the inelastic region. If demand is inelastic, raise the price (little quantity lost). If elastic, cut the price (lots of quantity gained). TR peaks where |PED| = 1. 要提高收益,把价格推向缺乏弹性的区域。若需求缺乏弹性,涨价(数量损失很少)。若富有弹性,降价(数量收获很多)。 TR 在 |PED| = 1 处达峰。 一 i The drug-interdiction application (Workshop) 缉毒应用案例(习题课) Demand for an addictive drug is inelastic. Cutting supply (interdiction) raises the price more than proportionally, so total expenditure on drugs - sellers' revenue - rises. Because users need more money to buy the same drugs, drug- related crime may increase. The elasticity sign drives the whole policy conclusion. 对成瘾性毒品的需求缺乏弹性。削减供给(缉毒)使价格不成比例地上升,所以毒品上的总支出 -- 卖方的收益 -- 上升。 因为吸毒者需要更多钱来买同样的毒品,与毒品相关的犯罪可能增加。弹性的符号驱动了整个政策结论。 ! PES is a ratio, not a multiplier PES 是比率,不是倍数 "PES = 2" means a 1% price rise raises quantity supplied by 2% - not that quantity doubles. The Workshop flags this as a T/F trap. Elasticity is always a percentage-on-percentage ratio. “PES= 2”意味着价格上升1% 使供给量上升 2% -- 而非数量翻倍。习题课把这标为判断题陷阱。弹性永远是百分比 对百分比的比率。 AskSia Library . ECB1101 · 双语 Bilingual CH 4 . WORKED MIDPOINT - - CHAPTER 4 (CONT. ) WORKED . QUIZ 1 STAPLE Worked example: the midpoint calculation 例题:中点法计算 DVD demand schedule - PED, then income elasticity, step by step DVD 需求表 -- PED,再算收入弹性,一步步来 This is the canonical Quiz 1 item, transcribed from the Week-4 Workshop: a demand schedule at two income levels. Read two rows, plug them into the midpoint formula, and classify. The numbers below match the Workshop's worked answers exactly. 这是经典的测验1题目,抄自第4周习题课(Workshop):两个收入水平下的需求表。读两行,代入中点公式,分类。下面的 数字与习题课的标准答案完全一致。 Price P Q at I = $10,000 Qa at I = $12,000 $8 $10
- 税负归宿（Tax incidence）一句话要会写：弹性更小的一方承担更多税负（因为更“走不了”）。[4]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfi 4 . A corrective tax = the external effect 4 · 矫正税 = 外部效应 A negative externality means SMC > PMC: the market over-produces. The fix is a Pigouvian tax = the marginal external cost (SMC - PMC, not the price gap), which lifts private cost to social cost and restores the efficient Q. Positive externality - subsidy = external benefit. Public good = non-rival + non- excludable - free-riding. ** 负外部性(negative externality) ** 意味着 ** SMC > PMC **: 市场 ** 生产过多 **。 对策是 ** 庇古税 (Pigouvian tax)= 边际外部成本 ** (SMC - PMC,* 不是*价格差),它把私人成本抬升至社会成本,恢复 有效的Q。正外部性→补贴=外部收益。公共物品 = 非竞争性+非排他性→搭便车(free-riding)。 AskSia Library . ECB1101 · 双语 Bilingual ✓ 2 . Elasticity by the midpoint method 2 . 用中点法(midpoint method)算弹性 ECB1101's default is the midpoint (arc) method: divide each %-change by the average of the two values. If demand is inelastic (|E| < 1), raise price to raise revenue; if elastic, cut it; TR peaks at |E| = 1. On a tax, the less-elastic side bears more - it cannot walk away. ECB1101 默认用 ** 中点法(arc method) **: 每个百分 比变化除以两值的 ** 平均 **。 若需求 ** 缺乏弹性 ** ([E]<1), ** 提价 ** 可增收入;若 ** 富有弹性 ** ,则 降价;TR在 | == 1时达到峰值。对于税收, ** 弹性 较小的一方承担更多 **-- 它无处可逃。 § 3 . P = MC competition / MR = MC monopoly 3 . 完全竞争 P = MC / 垄断 MR = MC A price taker has P = MR, so produces where P = MC; shut down if P < AVC; long run, free entry drives P to min ATC and profit to zero. A monopolist sets MR = MC for the quantity, then reads price off demand (MR = a - 2bQ, twice the slope). Because P > MC it under- produces - deadweight loss. ** 价格接受者(price taker) ** P = MR,故在 ** P = MC ** 处生产 ;** P <AVC 则停业(shut down) **; 长 期下自由进入将 P 压到 ** min ATC **、 利润压到 ** 零 **。** 垄断者(monopolist) ** 令 ** MR = MC ** 定数 量,再从 ** 需求曲线 ** 读出价格 (MR = a-2bQ,斜 率两倍)。因P>MC 而生产不足→无谓损失。 ✓ 5 . The four market structures at a glance 5 · 四种市场结构一览 Perfect competition: many firms, identical good, no barriers, P = MR = MC, zero LR profit. Monopolistic competition: many, differentiated, P > MC, excess capacity, zero LR profit (P = ATC tangency). Oligopoly: few firms, interdependent, market power. Monopoly: one firm, barriers, P > MR = MC, DWL. Markup (P - MC) > 0 for the last three. ** 完全竞争 **: 企业众多、产品同质、无壁垒,P= MR = MC,长期零利润 。** 垄断竞争 **: 众多、差异 化,P> MC,过剩产能,长期零利润(P=ATC相 切) 。** 寡头(oligopoly) **: 少数企业、相互依存、有 市场势力 。** 垄断 **: 单一企业、有壁垒,P> MR = MC,有 DWL。后三者加成(P-MC)>0。 ★ 6 . ALWAYS draw and fully label every Section-C graph 6 · C 部分每张图都要画出并完整标注 Axes named, both curves drawn, equilibrium marked, shifts shown with arrows, and CS / PS / DWL shaded and labelled. ECB1101 deducts marks for unlabelled axes, curves and movements - these are the easiest marks in the paper and an arithmetic slip cannot cost them. Draw the diagram even when the question does not explicitly ask. 坐标轴要命名, ** 两条曲线 ** 都画出,标出 ** 均衡点 ** , ** 用箭头表示移位 ** ,CS / PS / DWL ** 阴影并 标注 **。 ECB1101 ** 对未标注的坐标轴、曲线和移动 扣分 **-- 这些是全卷最易得的分,算术失误也夺不 走它们。即便题目没明说,也要画图。 ~1. 3 min PER MARK - PACE IT 每分 -- 把握节奏 130 min FOR 100 MARKS 对应 100 分 40 mk SECTION C - LEAVE TIME TO DRAW C 部分 -- 留时间画图 HURDLE - JUST BANK THE MARKS 门槛 -- 把分收下即可 ! Pace it: 100 marks in 130 minutes 把握节奏:130 分钟拿 100 分
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考试怎么考
- 从两行表用中点法算 PED → 分类 → 用 TR 法则判断该怎么动价格；
- 收入弹性/交叉弹性：分数往往在 符号（+ / -）上；要求你写步骤（每次除法都写）。[16]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfA demand curve tells you that quantity falls when price rises. Elasticity answers the next question - by how much? It converts a slope into a single, unit-free figure you can compute, compare across goods and tie directly to revenue. This is the most calculation-heavy week of the unit, and the engine of Quiz 1. 需求曲线告诉你价格上升时数量会下降。弹性(elasticity)回答下一个问题 -- 下降多少?它把斜率转化为一个可计算、可跨商 品比较、并直接与收益挂钩的无单位数字。这是本课程计算量最大的一周,也是测验1(Quiz 1)的引擎。 ★ What the exam asks here 这里考试问什么 Compute price elasticity of demand from a two-row schedule by the midpoint method; classify it as elastic / inelastic / unit-elastic; apply the total-revenue rule to say which way to move price; and read off income and cross-price elasticities by their sign. Quiz 1 (Week 5) is built almost entirely from this chapter - MCQ + a calculation + a graph. Answers are usually clean numbers and a calculator is allowed, so show every step. 用中点法从两行表算需求价格弹性;把它归类为富有弹性/缺乏弹性/单位弹性;应用总收益法则说出价格该往哪动; 并按符号读出收入和交叉价格弹性。测验1(第5周)几乎全部由本章构成 -- MCQ+一道计算+一张图。答案通常是干 净的数字且允许用计算器,所以每一步都要写出来。 4. 1 Price elasticity of demand - the midpoint method 4. 1 需求价格弹性(PED) –––中点法 The price elasticity of demand (PED) is the percentage change in quantity demanded divided by the percentage change in price. ECB1101 computes both percentages by the midpoint (arc) method: each change is divided by the average of the two values, not the starting value. 需求价格弹性(PED)是需求量的百分比变化除以价格的百分比变化。ECB1101 用中点(弧)法(midpoint method)算这两个百分 比:每个变化都除以两值的平均,而非起始值。 MIDPOINT (ARC) ELASTICITY PED where %4Q = (Q2-Q1) + [(Q1+Q2)/2] %AP %AP = (P2-P1) + [(P1+P2) /2] Because demand slopes down, %4Q and %AP have opposite signs, so PED is negative. The course classifies on the absolute value |PED|. AskSia Library · ECB1101 · 双语 Bilingual 由于需求向下倾斜,%△Q和%△P 符号相反,所以 PED 为负。课程按绝对值 |PED|来分类。 § Why ECB1101 uses the midpoint, not the point, formula ECB1101 为何用中点法而非点弹性公式 The midpoint method divides each change by the average of the start and end values. Its one virtue is direction- independence: the elasticity from $8-$10 equals the elasticity from $10-$8, because both use the same midpoint as the base. A plain %-change formula would give two different answers depending on which price you start from. This is the method the Workshop solutions and Quiz 1 use - match it exactly. 中点法把每个变化除以起止值的平均。它唯一的优点是方向无关:$8→$10 的弹性等于 $10→$8 的弹性,因为两者都以 同一个中点为基。普通的百分比变化公式会因你从哪个价格起算而给出两个不同答案。这是习题课答案和测验1所用的 方法 -- 精确匹配它。 The three regions 三个区域 | PED | Name Meaning > 1 Elastic Q responds more than proportionally to price = 1 Unit-elastic Q changes in the same proportion as price[12]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdf这些符号就是第3周的需求移动因素的数字化。某替代品价格上升使需求右移(EAB>0);某互补品价格上升使其左移 (EAB<O);收入提高使正常品需求右移(E1>0)。收入弹性<0是劣等品的标志 -- 所以“收入弹性总是正的”是错的。 - AskSia Library . ECB1101 · 双语 Bilingual ★ Exam move - the elasticity checklist 考试技巧 -- 弹性清单 (1) Identify which elasticity is asked - own-price, income, cross-price, or supply. (2) For every one, use the midpoint method: change + average, top and bottom. (3) For PED, take the absolute value and classify against 1, then apply the total-revenue rule. (4) For income / cross-price, the marks are in the sign: + or -, then name the good or relationship. Show every division - partial steps still earn marks. (1)辨明问的是哪种弹性 -- 自身价格、收入、交叉价格还是供给。(2)对每一种都用中点法:上下都是 变化÷平均。 (3)对 PED,取绝对值并与1比较分类,然后应用总收益法则。(4)对收入/交叉价格,分数在符号上:+或一,然后 说出商品或关系。把每次除法都写出来 -- 部分步骤仍能得分。 AskSia Library . ECB1101 · 双语 Bilingual CH 5 . SURPLUS - CHAPTER 5 . SURPLUS & MARKET EFFICIENCY EFFICIENCY Why the competitive market gets it right 竞争市场为何能达到最优 Consumer surplus, producer surplus and total surplus (TS) 消费者剩余(CS)、生产者剩余(PS)与社会总剩余(TS) IN ONE LINE Total surplus TS = CS + PS, and each piece is a triangle: CS is the area under demand above price, PS the area above supply below price. The competitive equilibrium Q* maximises TS; any other quantity wastes value - that wasted triangle is the deadweight loss. 社会总剩余 TS = CS+PS,每一块都是三角形:CS 是需求曲线下方、价格上方的面积,PS 是供给曲线上方、价格下 方的面积。竞争均衡的 Q*使 TS 最大化;任何其他数量都浪费价值 -- 那块被浪费的三角形就是无谓损失(DWL)。 A market does more than set a price - it creates value. Buyers pay less than the good is worth to them; sellers receive more than it cost them to supply. Add the two gains and you get total surplus (TS), the single number that measures how much a market benefits society. This chapter shows why the competitive equilibrium maximises TS - the result every later policy chapter measures against. 市场不只设定价格 -- 它还创造价值。买方支付的少于商品对他们的价值;卖方收到的多于其供给成本。把这两份所得相加, 就得到社会总剩余(TS),这个单一数字衡量市场让社会受益多少。本章说明为何竞争均衡使 TS 最大化 -- 这是往后每项政策 章节用来对照的结论。 ★ Why this chapter is the ruler for half the exam 为何本章是半张试卷的标尺 Surplus is the measuring stick every later topic uses. Taxes, price controls and externalities are all scored by how much total surplus they destroy - the deadweight loss. Get the three triangles automatic here and Chapter 6 becomes arithmetic. Quiz 2 (Week 7) opens with exactly this: CS, PS and TS read off a diagram. 剩余是往后每个主题都要用的量尺。税收、价格管制和外部性都按它们毁掉多少社会总剩余来评分 -- 即无谓损失。在 这里把三个三角形练到自动化,第6章就成了算术。测验 2(第7周)恰以此开场:从图上读出 CS、PS和 TS。 AskSia Library . ECB1101 · 双语 Bilingual Consumer surplus - what buyers gain 消费者剩余 -- 买方所得 Each buyer has a willingness to pay (WTP) - the height of the demand curve at that unit. They actually pay the market price. The difference is their gain. Summed over all units, consumer surplus is the area under demand and above price. 每个买方都有一个支付意愿(WTP) -- 即需求曲线在该单位 处的高度。他们实际支付市场价格。两者之差就是他们的所 得。对所有单位求和,消费者剩余就是需求曲线下方、价格 上方的面积。 Producer surplus - what sellers gain 生产者剩余 -- 卖方所得 Each seller has a willingness to sell (WTS) - their marginal cost, the height of the supply curve. They receive the market price; the gap is their gain. Summed, producer surplus is the area above supply and below price. 每个卖方都有一个出售意愿(WTS) -- 即其边际成本,也就 是供给曲线的高度。他们收到市场价格;差额就是他们的所 得。求和后,生产者剩余就是供给曲线上方、价格下方的面 积。
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Week 5 / Chapter 5：剩余 Surplus & 市场效率（半张卷的“尺子”）
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三个三角形：你要自动化
- 总剩余：$TS = CS + PS$。[12]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdf这些符号就是第3周的需求移动因素的数字化。某替代品价格上升使需求右移(EAB>0);某互补品价格上升使其左移 (EAB<O);收入提高使正常品需求右移(E1>0)。收入弹性<0是劣等品的标志 -- 所以“收入弹性总是正的”是错的。 - AskSia Library . ECB1101 · 双语 Bilingual ★ Exam move - the elasticity checklist 考试技巧 -- 弹性清单 (1) Identify which elasticity is asked - own-price, income, cross-price, or supply. (2) For every one, use the midpoint method: change + average, top and bottom. (3) For PED, take the absolute value and classify against 1, then apply the total-revenue rule. (4) For income / cross-price, the marks are in the sign: + or -, then name the good or relationship. Show every division - partial steps still earn marks. (1)辨明问的是哪种弹性 -- 自身价格、收入、交叉价格还是供给。(2)对每一种都用中点法:上下都是 变化÷平均。 (3)对 PED,取绝对值并与1比较分类,然后应用总收益法则。(4)对收入/交叉价格,分数在符号上:+或一,然后 说出商品或关系。把每次除法都写出来 -- 部分步骤仍能得分。 AskSia Library . ECB1101 · 双语 Bilingual CH 5 . SURPLUS - CHAPTER 5 . SURPLUS & MARKET EFFICIENCY EFFICIENCY Why the competitive market gets it right 竞争市场为何能达到最优 Consumer surplus, producer surplus and total surplus (TS) 消费者剩余(CS)、生产者剩余(PS)与社会总剩余(TS) IN ONE LINE Total surplus TS = CS + PS, and each piece is a triangle: CS is the area under demand above price, PS the area above supply below price. The competitive equilibrium Q* maximises TS; any other quantity wastes value - that wasted triangle is the deadweight loss. 社会总剩余 TS = CS+PS,每一块都是三角形:CS 是需求曲线下方、价格上方的面积,PS 是供给曲线上方、价格下 方的面积。竞争均衡的 Q*使 TS 最大化;任何其他数量都浪费价值 -- 那块被浪费的三角形就是无谓损失(DWL)。 A market does more than set a price - it creates value. Buyers pay less than the good is worth to them; sellers receive more than it cost them to supply. Add the two gains and you get total surplus (TS), the single number that measures how much a market benefits society. This chapter shows why the competitive equilibrium maximises TS - the result every later policy chapter measures against. 市场不只设定价格 -- 它还创造价值。买方支付的少于商品对他们的价值;卖方收到的多于其供给成本。把这两份所得相加, 就得到社会总剩余(TS),这个单一数字衡量市场让社会受益多少。本章说明为何竞争均衡使 TS 最大化 -- 这是往后每项政策 章节用来对照的结论。 ★ Why this chapter is the ruler for half the exam 为何本章是半张试卷的标尺 Surplus is the measuring stick every later topic uses. Taxes, price controls and externalities are all scored by how much total surplus they destroy - the deadweight loss. Get the three triangles automatic here and Chapter 6 becomes arithmetic. Quiz 2 (Week 7) opens with exactly this: CS, PS and TS read off a diagram. 剩余是往后每个主题都要用的量尺。税收、价格管制和外部性都按它们毁掉多少社会总剩余来评分 -- 即无谓损失。在 这里把三个三角形练到自动化,第6章就成了算术。测验 2(第7周)恰以此开场:从图上读出 CS、PS和 TS。 AskSia Library . ECB1101 · 双语 Bilingual Consumer surplus - what buyers gain 消费者剩余 -- 买方所得 Each buyer has a willingness to pay (WTP) - the height of the demand curve at that unit. They actually pay the market price. The difference is their gain. Summed over all units, consumer surplus is the area under demand and above price. 每个买方都有一个支付意愿(WTP) -- 即需求曲线在该单位 处的高度。他们实际支付市场价格。两者之差就是他们的所 得。对所有单位求和,消费者剩余就是需求曲线下方、价格 上方的面积。 Producer surplus - what sellers gain 生产者剩余 -- 卖方所得 Each seller has a willingness to sell (WTS) - their marginal cost, the height of the supply curve. They receive the market price; the gap is their gain. Summed, producer surplus is the area above supply and below price. 每个卖方都有一个出售意愿(WTS) -- 即其边际成本,也就 是供给曲线的高度。他们收到市场价格;差额就是他们的所 得。求和后,生产者剩余就是供给曲线上方、价格下方的面 积。
- CS（消费者剩余）：需求曲线下方、价格上方的面积。[12]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdf这些符号就是第3周的需求移动因素的数字化。某替代品价格上升使需求右移(EAB>0);某互补品价格上升使其左移 (EAB<O);收入提高使正常品需求右移(E1>0)。收入弹性<0是劣等品的标志 -- 所以“收入弹性总是正的”是错的。 - AskSia Library . ECB1101 · 双语 Bilingual ★ Exam move - the elasticity checklist 考试技巧 -- 弹性清单 (1) Identify which elasticity is asked - own-price, income, cross-price, or supply. (2) For every one, use the midpoint method: change + average, top and bottom. (3) For PED, take the absolute value and classify against 1, then apply the total-revenue rule. (4) For income / cross-price, the marks are in the sign: + or -, then name the good or relationship. Show every division - partial steps still earn marks. (1)辨明问的是哪种弹性 -- 自身价格、收入、交叉价格还是供给。(2)对每一种都用中点法:上下都是 变化÷平均。 (3)对 PED,取绝对值并与1比较分类,然后应用总收益法则。(4)对收入/交叉价格,分数在符号上:+或一,然后 说出商品或关系。把每次除法都写出来 -- 部分步骤仍能得分。 AskSia Library . ECB1101 · 双语 Bilingual CH 5 . SURPLUS - CHAPTER 5 . SURPLUS & MARKET EFFICIENCY EFFICIENCY Why the competitive market gets it right 竞争市场为何能达到最优 Consumer surplus, producer surplus and total surplus (TS) 消费者剩余(CS)、生产者剩余(PS)与社会总剩余(TS) IN ONE LINE Total surplus TS = CS + PS, and each piece is a triangle: CS is the area under demand above price, PS the area above supply below price. The competitive equilibrium Q* maximises TS; any other quantity wastes value - that wasted triangle is the deadweight loss. 社会总剩余 TS = CS+PS,每一块都是三角形:CS 是需求曲线下方、价格上方的面积,PS 是供给曲线上方、价格下 方的面积。竞争均衡的 Q*使 TS 最大化;任何其他数量都浪费价值 -- 那块被浪费的三角形就是无谓损失(DWL)。 A market does more than set a price - it creates value. Buyers pay less than the good is worth to them; sellers receive more than it cost them to supply. Add the two gains and you get total surplus (TS), the single number that measures how much a market benefits society. This chapter shows why the competitive equilibrium maximises TS - the result every later policy chapter measures against. 市场不只设定价格 -- 它还创造价值。买方支付的少于商品对他们的价值;卖方收到的多于其供给成本。把这两份所得相加, 就得到社会总剩余(TS),这个单一数字衡量市场让社会受益多少。本章说明为何竞争均衡使 TS 最大化 -- 这是往后每项政策 章节用来对照的结论。 ★ Why this chapter is the ruler for half the exam 为何本章是半张试卷的标尺 Surplus is the measuring stick every later topic uses. Taxes, price controls and externalities are all scored by how much total surplus they destroy - the deadweight loss. Get the three triangles automatic here and Chapter 6 becomes arithmetic. Quiz 2 (Week 7) opens with exactly this: CS, PS and TS read off a diagram. 剩余是往后每个主题都要用的量尺。税收、价格管制和外部性都按它们毁掉多少社会总剩余来评分 -- 即无谓损失。在 这里把三个三角形练到自动化,第6章就成了算术。测验 2(第7周)恰以此开场:从图上读出 CS、PS和 TS。 AskSia Library . ECB1101 · 双语 Bilingual Consumer surplus - what buyers gain 消费者剩余 -- 买方所得 Each buyer has a willingness to pay (WTP) - the height of the demand curve at that unit. They actually pay the market price. The difference is their gain. Summed over all units, consumer surplus is the area under demand and above price. 每个买方都有一个支付意愿(WTP) -- 即需求曲线在该单位 处的高度。他们实际支付市场价格。两者之差就是他们的所 得。对所有单位求和,消费者剩余就是需求曲线下方、价格 上方的面积。 Producer surplus - what sellers gain 生产者剩余 -- 卖方所得 Each seller has a willingness to sell (WTS) - their marginal cost, the height of the supply curve. They receive the market price; the gap is their gain. Summed, producer surplus is the area above supply and below price. 每个卖方都有一个出售意愿(WTS) -- 即其边际成本,也就 是供给曲线的高度。他们收到市场价格;差额就是他们的所 得。求和后,生产者剩余就是供给曲线上方、价格下方的面 积。
- PS（生产者剩余）：供给曲线上方、价格下方的面积。[12]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdf这些符号就是第3周的需求移动因素的数字化。某替代品价格上升使需求右移(EAB>0);某互补品价格上升使其左移 (EAB<O);收入提高使正常品需求右移(E1>0)。收入弹性<0是劣等品的标志 -- 所以“收入弹性总是正的”是错的。 - AskSia Library . ECB1101 · 双语 Bilingual ★ Exam move - the elasticity checklist 考试技巧 -- 弹性清单 (1) Identify which elasticity is asked - own-price, income, cross-price, or supply. (2) For every one, use the midpoint method: change + average, top and bottom. (3) For PED, take the absolute value and classify against 1, then apply the total-revenue rule. (4) For income / cross-price, the marks are in the sign: + or -, then name the good or relationship. Show every division - partial steps still earn marks. (1)辨明问的是哪种弹性 -- 自身价格、收入、交叉价格还是供给。(2)对每一种都用中点法:上下都是 变化÷平均。 (3)对 PED,取绝对值并与1比较分类,然后应用总收益法则。(4)对收入/交叉价格,分数在符号上:+或一,然后 说出商品或关系。把每次除法都写出来 -- 部分步骤仍能得分。 AskSia Library . ECB1101 · 双语 Bilingual CH 5 . SURPLUS - CHAPTER 5 . SURPLUS & MARKET EFFICIENCY EFFICIENCY Why the competitive market gets it right 竞争市场为何能达到最优 Consumer surplus, producer surplus and total surplus (TS) 消费者剩余(CS)、生产者剩余(PS)与社会总剩余(TS) IN ONE LINE Total surplus TS = CS + PS, and each piece is a triangle: CS is the area under demand above price, PS the area above supply below price. The competitive equilibrium Q* maximises TS; any other quantity wastes value - that wasted triangle is the deadweight loss. 社会总剩余 TS = CS+PS,每一块都是三角形:CS 是需求曲线下方、价格上方的面积,PS 是供给曲线上方、价格下 方的面积。竞争均衡的 Q*使 TS 最大化;任何其他数量都浪费价值 -- 那块被浪费的三角形就是无谓损失(DWL)。 A market does more than set a price - it creates value. Buyers pay less than the good is worth to them; sellers receive more than it cost them to supply. Add the two gains and you get total surplus (TS), the single number that measures how much a market benefits society. This chapter shows why the competitive equilibrium maximises TS - the result every later policy chapter measures against. 市场不只设定价格 -- 它还创造价值。买方支付的少于商品对他们的价值;卖方收到的多于其供给成本。把这两份所得相加, 就得到社会总剩余(TS),这个单一数字衡量市场让社会受益多少。本章说明为何竞争均衡使 TS 最大化 -- 这是往后每项政策 章节用来对照的结论。 ★ Why this chapter is the ruler for half the exam 为何本章是半张试卷的标尺 Surplus is the measuring stick every later topic uses. Taxes, price controls and externalities are all scored by how much total surplus they destroy - the deadweight loss. Get the three triangles automatic here and Chapter 6 becomes arithmetic. Quiz 2 (Week 7) opens with exactly this: CS, PS and TS read off a diagram. 剩余是往后每个主题都要用的量尺。税收、价格管制和外部性都按它们毁掉多少社会总剩余来评分 -- 即无谓损失。在 这里把三个三角形练到自动化,第6章就成了算术。测验 2(第7周)恰以此开场:从图上读出 CS、PS和 TS。 AskSia Library . ECB1101 · 双语 Bilingual Consumer surplus - what buyers gain 消费者剩余 -- 买方所得 Each buyer has a willingness to pay (WTP) - the height of the demand curve at that unit. They actually pay the market price. The difference is their gain. Summed over all units, consumer surplus is the area under demand and above price. 每个买方都有一个支付意愿(WTP) -- 即需求曲线在该单位 处的高度。他们实际支付市场价格。两者之差就是他们的所 得。对所有单位求和,消费者剩余就是需求曲线下方、价格 上方的面积。 Producer surplus - what sellers gain 生产者剩余 -- 卖方所得 Each seller has a willingness to sell (WTS) - their marginal cost, the height of the supply curve. They receive the market price; the gap is their gain. Summed, producer surplus is the area above supply and below price. 每个卖方都有一个出售意愿(WTS) -- 即其边际成本,也就 是供给曲线的高度。他们收到市场价格;差额就是他们的所 得。求和后,生产者剩余就是供给曲线上方、价格下方的面 积。
- 都是三角形面积：$ \frac12 \times \text{底} \times \text{高}$（题库解答就是这么算）。[11]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdf这正是测验 2(Quiz 2)沿用的结构,出自第 5周习题课:从线性图上读出均衡和需求截距,计算三个三角形面积,再在需求移 动后重算一遍。下面的数字与习题课答案一致。 I 1 Equilibrium. The linear D and S cross at P* = 18, Q* = 36; the demand curve hits the price axis at Pmax = 36, and supply runs from the origin (Pmin = 0). ** 均衡 。** 线性 D与 S 相交于 ** P *= 18, Q *= 36 **; 需求曲线在价格轴上交于 ** Pmax = 36 ** ,供给自原点起 (Pmin = 0). - 2 Consumer surplus. Triangle from P* = 18 up to Pmax = 36, over Q* = 36: CS = 1/2 × 36 x (36 - 18) = 1/2 × 36 × 18 = 324. - ** 消费者剩余 。** 从 P* = 18 向上到 Pmax = 36、底为 Q* = 36 的三角形:CS= 1/2 ×36×(36-18)=1/2 × 36× 18 = ** 324 **. 3 Producer surplus. Triangle from Pmin = 0 up to P* = 18, over Q* = 36: PS = 1/2 x 36 x (18 - 0) = 324. ** 生产者剩余 。** 从 Pmin =0 向上到 P* = 18、底为 Q* = 36 的三角形:PS =1/2 ×36×(18-0) =** 324 **。 4 Total surplus. TS = 324 + 324 = 648 - and this is the maximum: no other quantity yields more. ** 社会总剩余 。** TS = 324+ 324 =** 648 **-- 这是 ** 最大值 **: 没有其他数量能产生更多。 5 Demand falls 12 units at every price (a leftward shift). New equilibrium: P* = 15, Q* = 30. ** 需求在每个价格上减少 12 单位 ** (向左移位)。新均衡: ** P* = 15, Q *= 30 **. 6 Recompute. CS = 1/2 x 30 x (30 - 15) = 225; PS = 1/2 x 30 x 15 = 225; TS = 450 - all three fall. Price ($) S CS PS D Quantity Before: P* = 18, Q* = 36, demand intercept 36. CS (blue) = 324, PS (green) = 324, so TS = 648. The two triangles are equal because demand and supply are equally steep. 之前: ** P* = 18, Q *= 36 ** ,需求截距 36。CS (蓝)= 324,PS(绿)=324,故 ** TS = 648 **。 两个三角形相等,因为需求与供给同样陡峭。 I CS I PS After demand falls 12 units - P* = 15, Q* = 30 Working Value Consumer surplus - · 30 · 15 1/2 × 30 x (30 - 15) Producer surplus - 1/2 × 30 × (15-0) 불 · 30 · 15 Total surplus TS = CS + PS
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“效率”结论（必须会说会画）
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典型计算套路（你要练到 1 分钟能写完）
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Week 6（高频 Section C）：税 Tax、税楔 Wedge、税收收入与 DWL
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必背“税题四步法”（Section C 常见模板）
- Step 1：先求自由市场均衡（$Q_d=Q_s$ 得 $P^*,Q^*$）。[14]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdf(a) Find P* and Q*, and draw the labelled diagram. [5] (b) The government imposes a $10 per-unit tax. Find Pb, Ps and the new quantity, and shade tax revenue and DWL on your graph. [8] (c) Calculate tax revenue and deadweight loss. [4] (d) In one sentence, explain why the DWL arises. [3] (a) 求 P* 与Q*,并画出带标注的图。[5] (b)政府征收一项$10 的从量税。求 Pb、Ps 与新数量,并在图上对税收收入 和 DWL 着色。[8](c)计算税收收入与无谓损失。[4](d)用一句话解释 DWL 为何产生。[3] WORKED SOLUTION 1 (a) Equilibrium. 60 - P = P -+ 60 = 2P - P* = 30; Q* = 30. ** (a) 均衡 。** 60 -P =P → 60= 2P→ ** P* = 30 **; Q* = ** 30 **. 2 (b) The wedge. Pb = Ps + 10 and 60 - Pb = Ps ++ 60 - (Ps + 10) = Ps - 50 = 2Ps - Ps = 25, Pb = 35. New Q = 60 - 35 = 25. ** (b)税楔 。** Pb = Ps + 10 且 60 - Pb = Ps → 60 -(Ps + 10) = Ps -> 50 = 2Ps -> *Ps = 25*, *Pb = 35 **. 新Q=60-35 =** 25 **。 3 (c) Revenue & DWL. Revenue = 10 × 25 = 250; DWL = 1/2 × 10 x(30-25) =1/2 ×10×5=25. ** (c) 收入与 DWL 。** 收入=10×25 =** 250 **; DWL = 1/2 × 10 x (30 - 25) = 1/2 x 10 × 5 = ** 25 **. 4 (d) Why DWL. The tax stops 5 mutually beneficial trades (Q 30-25) whose value to buyers exceeded their cost to sellers; that surplus is lost to everyone - it is not transferred, it simply disappears. Price ($) S $35 $25 D Quantity Buyers pay $35, sellers keep $25, Q falls 30 - 25. Amber rectangle = tax revenue (250); red triangle = deadweight loss (25). 买方付 ** $35 ** ,卖方留 ** $25 ** ,Q由 30→ 25 下 降。琥珀色矩形= 税收收入( ** 250 ** );红色三角形= 无谓损失( ** 25 ** )。 I tax revenue I deadweight loss AskSia Library · ECB1101 · 双语 Bilingual ** (d) 为何有 DWL 。** 税收阻止了5 笔互利交易(Q 30→25),这些交易对买方的价值超过对卖方的成本;那部 分剩余对 ** 所有人 ** 都损失了 -- 它没有被转移,而是直接 消失。 ★ What to LABEL for full marks (ECB1101 deducts for missing labels) 为拿满分该标注什么 (ECB1101 漏标会扣分) Axes: Price ($) on the vertical, Quantity on the horizontal. Both curves named D and S. Original equilibrium (P* = 30, Q* = 30) dotted to the axes. After the tax, mark Pb = 35 and Ps = 25 on the price axis and Q = 25 on the quantity axis. Shade and label the tax-revenue rectangle and the DWL triangle. State the tax wedge (the $10 vertical gap) explicitly - that gap is the whole story. ** 坐标轴 :** 纵轴为价格($),横轴为数量 。** 两条曲线 ** 分别标 D 和 S 。** 原均衡 ** (P *= 30,Q *= 30)用虚线连到坐 标轴。征税后,在价格轴上标出 ** Pb = 35 ** 和 ** Ps = 25 ** ,在数量轴上标出 ** Q= 25 **。** 阴影并标注 ** 税收收 入矩形和 DWL 三角形。明确写出 ** 税楔(tax wedge) ** (那$10的垂直缺口) -- 这个缺口就是全部要点。 ! The tax-revenue area is a rectangle, the DWL is a triangle 税收面积是矩形,DWL 是三角形 Tax revenue = t x new Q (a rectangle, height = the wedge, base = the smaller quantity). DWL = 1/2 x t x AQ (the triangle to the right, between the curves, over the lost trades). Mixing the bases - using the old quantity for revenue or the old quantity in the DWL base - is the most common Section-C slip. 税收收入= ** t x 新 Q ** (一个矩形,高=税楔,底=较小的数量)。DWL= ** 1/2 x t x△Q ** (右侧、两曲线之间、 覆盖损失交易的三角形)。混淆底边 -- 给收入用旧数量,或在 DWL 底边用旧数量 -- 是 C 部分最常见的失误。 AskSia Library . ECB1101 · 双语 Bilingual
- Step 2：写“税楔”关系（wedge）：
- Step 3：求新数量（把 $P_b,P_s$ 代回需求/供给求 $Q_{new}$）。[14]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdf(a) Find P* and Q*, and draw the labelled diagram. [5] (b) The government imposes a $10 per-unit tax. Find Pb, Ps and the new quantity, and shade tax revenue and DWL on your graph. [8] (c) Calculate tax revenue and deadweight loss. [4] (d) In one sentence, explain why the DWL arises. [3] (a) 求 P* 与Q*,并画出带标注的图。[5] (b)政府征收一项$10 的从量税。求 Pb、Ps 与新数量,并在图上对税收收入 和 DWL 着色。[8](c)计算税收收入与无谓损失。[4](d)用一句话解释 DWL 为何产生。[3] WORKED SOLUTION 1 (a) Equilibrium. 60 - P = P -+ 60 = 2P - P* = 30; Q* = 30. ** (a) 均衡 。** 60 -P =P → 60= 2P→ ** P* = 30 **; Q* = ** 30 **. 2 (b) The wedge. Pb = Ps + 10 and 60 - Pb = Ps ++ 60 - (Ps + 10) = Ps - 50 = 2Ps - Ps = 25, Pb = 35. New Q = 60 - 35 = 25. ** (b)税楔 。** Pb = Ps + 10 且 60 - Pb = Ps → 60 -(Ps + 10) = Ps -> 50 = 2Ps -> *Ps = 25*, *Pb = 35 **. 新Q=60-35 =** 25 **。 3 (c) Revenue & DWL. Revenue = 10 × 25 = 250; DWL = 1/2 × 10 x(30-25) =1/2 ×10×5=25. ** (c) 收入与 DWL 。** 收入=10×25 =** 250 **; DWL = 1/2 × 10 x (30 - 25) = 1/2 x 10 × 5 = ** 25 **. 4 (d) Why DWL. The tax stops 5 mutually beneficial trades (Q 30-25) whose value to buyers exceeded their cost to sellers; that surplus is lost to everyone - it is not transferred, it simply disappears. Price ($) S $35 $25 D Quantity Buyers pay $35, sellers keep $25, Q falls 30 - 25. Amber rectangle = tax revenue (250); red triangle = deadweight loss (25). 买方付 ** $35 ** ,卖方留 ** $25 ** ,Q由 30→ 25 下 降。琥珀色矩形= 税收收入( ** 250 ** );红色三角形= 无谓损失( ** 25 ** )。 I tax revenue I deadweight loss AskSia Library · ECB1101 · 双语 Bilingual ** (d) 为何有 DWL 。** 税收阻止了5 笔互利交易(Q 30→25),这些交易对买方的价值超过对卖方的成本;那部 分剩余对 ** 所有人 ** 都损失了 -- 它没有被转移,而是直接 消失。 ★ What to LABEL for full marks (ECB1101 deducts for missing labels) 为拿满分该标注什么 (ECB1101 漏标会扣分) Axes: Price ($) on the vertical, Quantity on the horizontal. Both curves named D and S. Original equilibrium (P* = 30, Q* = 30) dotted to the axes. After the tax, mark Pb = 35 and Ps = 25 on the price axis and Q = 25 on the quantity axis. Shade and label the tax-revenue rectangle and the DWL triangle. State the tax wedge (the $10 vertical gap) explicitly - that gap is the whole story. ** 坐标轴 :** 纵轴为价格($),横轴为数量 。** 两条曲线 ** 分别标 D 和 S 。** 原均衡 ** (P *= 30,Q *= 30)用虚线连到坐 标轴。征税后,在价格轴上标出 ** Pb = 35 ** 和 ** Ps = 25 ** ,在数量轴上标出 ** Q= 25 **。** 阴影并标注 ** 税收收 入矩形和 DWL 三角形。明确写出 ** 税楔(tax wedge) ** (那$10的垂直缺口) -- 这个缺口就是全部要点。 ! The tax-revenue area is a rectangle, the DWL is a triangle 税收面积是矩形,DWL 是三角形 Tax revenue = t x new Q (a rectangle, height = the wedge, base = the smaller quantity). DWL = 1/2 x t x AQ (the triangle to the right, between the curves, over the lost trades). Mixing the bases - using the old quantity for revenue or the old quantity in the DWL base - is the most common Section-C slip. 税收收入= ** t x 新 Q ** (一个矩形,高=税楔,底=较小的数量)。DWL= ** 1/2 x t x△Q ** (右侧、两曲线之间、 覆盖损失交易的三角形)。混淆底边 -- 给收入用旧数量,或在 DWL 底边用旧数量 -- 是 C 部分最常见的失误。 AskSia Library . ECB1101 · 双语 Bilingual
- Step 4：算面积：
- 税收收入（矩形）：$\text{Revenue}=t \times Q_{new}$。[14]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdf(a) Find P* and Q*, and draw the labelled diagram. [5] (b) The government imposes a $10 per-unit tax. Find Pb, Ps and the new quantity, and shade tax revenue and DWL on your graph. [8] (c) Calculate tax revenue and deadweight loss. [4] (d) In one sentence, explain why the DWL arises. [3] (a) 求 P* 与Q*,并画出带标注的图。[5] (b)政府征收一项$10 的从量税。求 Pb、Ps 与新数量,并在图上对税收收入 和 DWL 着色。[8](c)计算税收收入与无谓损失。[4](d)用一句话解释 DWL 为何产生。[3] WORKED SOLUTION 1 (a) Equilibrium. 60 - P = P -+ 60 = 2P - P* = 30; Q* = 30. ** (a) 均衡 。** 60 -P =P → 60= 2P→ ** P* = 30 **; Q* = ** 30 **. 2 (b) The wedge. Pb = Ps + 10 and 60 - Pb = Ps ++ 60 - (Ps + 10) = Ps - 50 = 2Ps - Ps = 25, Pb = 35. New Q = 60 - 35 = 25. ** (b)税楔 。** Pb = Ps + 10 且 60 - Pb = Ps → 60 -(Ps + 10) = Ps -> 50 = 2Ps -> *Ps = 25*, *Pb = 35 **. 新Q=60-35 =** 25 **。 3 (c) Revenue & DWL. Revenue = 10 × 25 = 250; DWL = 1/2 × 10 x(30-25) =1/2 ×10×5=25. ** (c) 收入与 DWL 。** 收入=10×25 =** 250 **; DWL = 1/2 × 10 x (30 - 25) = 1/2 x 10 × 5 = ** 25 **. 4 (d) Why DWL. The tax stops 5 mutually beneficial trades (Q 30-25) whose value to buyers exceeded their cost to sellers; that surplus is lost to everyone - it is not transferred, it simply disappears. Price ($) S $35 $25 D Quantity Buyers pay $35, sellers keep $25, Q falls 30 - 25. Amber rectangle = tax revenue (250); red triangle = deadweight loss (25). 买方付 ** $35 ** ,卖方留 ** $25 ** ,Q由 30→ 25 下 降。琥珀色矩形= 税收收入( ** 250 ** );红色三角形= 无谓损失( ** 25 ** )。 I tax revenue I deadweight loss AskSia Library · ECB1101 · 双语 Bilingual ** (d) 为何有 DWL 。** 税收阻止了5 笔互利交易(Q 30→25),这些交易对买方的价值超过对卖方的成本;那部 分剩余对 ** 所有人 ** 都损失了 -- 它没有被转移,而是直接 消失。 ★ What to LABEL for full marks (ECB1101 deducts for missing labels) 为拿满分该标注什么 (ECB1101 漏标会扣分) Axes: Price ($) on the vertical, Quantity on the horizontal. Both curves named D and S. Original equilibrium (P* = 30, Q* = 30) dotted to the axes. After the tax, mark Pb = 35 and Ps = 25 on the price axis and Q = 25 on the quantity axis. Shade and label the tax-revenue rectangle and the DWL triangle. State the tax wedge (the $10 vertical gap) explicitly - that gap is the whole story. ** 坐标轴 :** 纵轴为价格($),横轴为数量 。** 两条曲线 ** 分别标 D 和 S 。** 原均衡 ** (P *= 30,Q *= 30)用虚线连到坐 标轴。征税后,在价格轴上标出 ** Pb = 35 ** 和 ** Ps = 25 ** ,在数量轴上标出 ** Q= 25 **。** 阴影并标注 ** 税收收 入矩形和 DWL 三角形。明确写出 ** 税楔(tax wedge) ** (那$10的垂直缺口) -- 这个缺口就是全部要点。 ! The tax-revenue area is a rectangle, the DWL is a triangle 税收面积是矩形,DWL 是三角形 Tax revenue = t x new Q (a rectangle, height = the wedge, base = the smaller quantity). DWL = 1/2 x t x AQ (the triangle to the right, between the curves, over the lost trades). Mixing the bases - using the old quantity for revenue or the old quantity in the DWL base - is the most common Section-C slip. 税收收入= ** t x 新 Q ** (一个矩形,高=税楔,底=较小的数量)。DWL= ** 1/2 x t x△Q ** (右侧、两曲线之间、 覆盖损失交易的三角形)。混淆底边 -- 给收入用旧数量,或在 DWL 底边用旧数量 -- 是 C 部分最常见的失误。 AskSia Library . ECB1101 · 双语 Bilingual
- 无谓损失（右侧三角形）：$DWL=\frac12 \times t \times \Delta Q$。[14]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdf(a) Find P* and Q*, and draw the labelled diagram. [5] (b) The government imposes a $10 per-unit tax. Find Pb, Ps and the new quantity, and shade tax revenue and DWL on your graph. [8] (c) Calculate tax revenue and deadweight loss. [4] (d) In one sentence, explain why the DWL arises. [3] (a) 求 P* 与Q*,并画出带标注的图。[5] (b)政府征收一项$10 的从量税。求 Pb、Ps 与新数量,并在图上对税收收入 和 DWL 着色。[8](c)计算税收收入与无谓损失。[4](d)用一句话解释 DWL 为何产生。[3] WORKED SOLUTION 1 (a) Equilibrium. 60 - P = P -+ 60 = 2P - P* = 30; Q* = 30. ** (a) 均衡 。** 60 -P =P → 60= 2P→ ** P* = 30 **; Q* = ** 30 **. 2 (b) The wedge. Pb = Ps + 10 and 60 - Pb = Ps ++ 60 - (Ps + 10) = Ps - 50 = 2Ps - Ps = 25, Pb = 35. New Q = 60 - 35 = 25. ** (b)税楔 。** Pb = Ps + 10 且 60 - Pb = Ps → 60 -(Ps + 10) = Ps -> 50 = 2Ps -> *Ps = 25*, *Pb = 35 **. 新Q=60-35 =** 25 **。 3 (c) Revenue & DWL. Revenue = 10 × 25 = 250; DWL = 1/2 × 10 x(30-25) =1/2 ×10×5=25. ** (c) 收入与 DWL 。** 收入=10×25 =** 250 **; DWL = 1/2 × 10 x (30 - 25) = 1/2 x 10 × 5 = ** 25 **. 4 (d) Why DWL. The tax stops 5 mutually beneficial trades (Q 30-25) whose value to buyers exceeded their cost to sellers; that surplus is lost to everyone - it is not transferred, it simply disappears. Price ($) S $35 $25 D Quantity Buyers pay $35, sellers keep $25, Q falls 30 - 25. Amber rectangle = tax revenue (250); red triangle = deadweight loss (25). 买方付 ** $35 ** ,卖方留 ** $25 ** ,Q由 30→ 25 下 降。琥珀色矩形= 税收收入( ** 250 ** );红色三角形= 无谓损失( ** 25 ** )。 I tax revenue I deadweight loss AskSia Library · ECB1101 · 双语 Bilingual ** (d) 为何有 DWL 。** 税收阻止了5 笔互利交易(Q 30→25),这些交易对买方的价值超过对卖方的成本;那部 分剩余对 ** 所有人 ** 都损失了 -- 它没有被转移,而是直接 消失。 ★ What to LABEL for full marks (ECB1101 deducts for missing labels) 为拿满分该标注什么 (ECB1101 漏标会扣分) Axes: Price ($) on the vertical, Quantity on the horizontal. Both curves named D and S. Original equilibrium (P* = 30, Q* = 30) dotted to the axes. After the tax, mark Pb = 35 and Ps = 25 on the price axis and Q = 25 on the quantity axis. Shade and label the tax-revenue rectangle and the DWL triangle. State the tax wedge (the $10 vertical gap) explicitly - that gap is the whole story. ** 坐标轴 :** 纵轴为价格($),横轴为数量 。** 两条曲线 ** 分别标 D 和 S 。** 原均衡 ** (P *= 30,Q *= 30)用虚线连到坐 标轴。征税后,在价格轴上标出 ** Pb = 35 ** 和 ** Ps = 25 ** ,在数量轴上标出 ** Q= 25 **。** 阴影并标注 ** 税收收 入矩形和 DWL 三角形。明确写出 ** 税楔(tax wedge) ** (那$10的垂直缺口) -- 这个缺口就是全部要点。 ! The tax-revenue area is a rectangle, the DWL is a triangle 税收面积是矩形,DWL 是三角形 Tax revenue = t x new Q (a rectangle, height = the wedge, base = the smaller quantity). DWL = 1/2 x t x AQ (the triangle to the right, between the curves, over the lost trades). Mixing the bases - using the old quantity for revenue or the old quantity in the DWL base - is the most common Section-C slip. 税收收入= ** t x 新 Q ** (一个矩形,高=税楔,底=较小的数量)。DWL= ** 1/2 x t x△Q ** (右侧、两曲线之间、 覆盖损失交易的三角形)。混淆底边 -- 给收入用旧数量,或在 DWL 底边用旧数量 -- 是 C 部分最常见的失误。 AskSia Library . ECB1101 · 双语 Bilingual
- “一句话解释 DWL 为何出现”：税阻止了部分互利交易，那部分剩余 不是转移，而是 直接消失。[14]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdf(a) Find P* and Q*, and draw the labelled diagram. [5] (b) The government imposes a $10 per-unit tax. Find Pb, Ps and the new quantity, and shade tax revenue and DWL on your graph. [8] (c) Calculate tax revenue and deadweight loss. [4] (d) In one sentence, explain why the DWL arises. [3] (a) 求 P* 与Q*,并画出带标注的图。[5] (b)政府征收一项$10 的从量税。求 Pb、Ps 与新数量,并在图上对税收收入 和 DWL 着色。[8](c)计算税收收入与无谓损失。[4](d)用一句话解释 DWL 为何产生。[3] WORKED SOLUTION 1 (a) Equilibrium. 60 - P = P -+ 60 = 2P - P* = 30; Q* = 30. ** (a) 均衡 。** 60 -P =P → 60= 2P→ ** P* = 30 **; Q* = ** 30 **. 2 (b) The wedge. Pb = Ps + 10 and 60 - Pb = Ps ++ 60 - (Ps + 10) = Ps - 50 = 2Ps - Ps = 25, Pb = 35. New Q = 60 - 35 = 25. ** (b)税楔 。** Pb = Ps + 10 且 60 - Pb = Ps → 60 -(Ps + 10) = Ps -> 50 = 2Ps -> *Ps = 25*, *Pb = 35 **. 新Q=60-35 =** 25 **。 3 (c) Revenue & DWL. Revenue = 10 × 25 = 250; DWL = 1/2 × 10 x(30-25) =1/2 ×10×5=25. ** (c) 收入与 DWL 。** 收入=10×25 =** 250 **; DWL = 1/2 × 10 x (30 - 25) = 1/2 x 10 × 5 = ** 25 **. 4 (d) Why DWL. The tax stops 5 mutually beneficial trades (Q 30-25) whose value to buyers exceeded their cost to sellers; that surplus is lost to everyone - it is not transferred, it simply disappears. Price ($) S $35 $25 D Quantity Buyers pay $35, sellers keep $25, Q falls 30 - 25. Amber rectangle = tax revenue (250); red triangle = deadweight loss (25). 买方付 ** $35 ** ,卖方留 ** $25 ** ,Q由 30→ 25 下 降。琥珀色矩形= 税收收入( ** 250 ** );红色三角形= 无谓损失( ** 25 ** )。 I tax revenue I deadweight loss AskSia Library · ECB1101 · 双语 Bilingual ** (d) 为何有 DWL 。** 税收阻止了5 笔互利交易(Q 30→25),这些交易对买方的价值超过对卖方的成本;那部 分剩余对 ** 所有人 ** 都损失了 -- 它没有被转移,而是直接 消失。 ★ What to LABEL for full marks (ECB1101 deducts for missing labels) 为拿满分该标注什么 (ECB1101 漏标会扣分) Axes: Price ($) on the vertical, Quantity on the horizontal. Both curves named D and S. Original equilibrium (P* = 30, Q* = 30) dotted to the axes. After the tax, mark Pb = 35 and Ps = 25 on the price axis and Q = 25 on the quantity axis. Shade and label the tax-revenue rectangle and the DWL triangle. State the tax wedge (the $10 vertical gap) explicitly - that gap is the whole story. ** 坐标轴 :** 纵轴为价格($),横轴为数量 。** 两条曲线 ** 分别标 D 和 S 。** 原均衡 ** (P *= 30,Q *= 30)用虚线连到坐 标轴。征税后,在价格轴上标出 ** Pb = 35 ** 和 ** Ps = 25 ** ,在数量轴上标出 ** Q= 25 **。** 阴影并标注 ** 税收收 入矩形和 DWL 三角形。明确写出 ** 税楔(tax wedge) ** (那$10的垂直缺口) -- 这个缺口就是全部要点。 ! The tax-revenue area is a rectangle, the DWL is a triangle 税收面积是矩形,DWL 是三角形 Tax revenue = t x new Q (a rectangle, height = the wedge, base = the smaller quantity). DWL = 1/2 x t x AQ (the triangle to the right, between the curves, over the lost trades). Mixing the bases - using the old quantity for revenue or the old quantity in the DWL base - is the most common Section-C slip. 税收收入= ** t x 新 Q ** (一个矩形,高=税楔,底=较小的数量)。DWL= ** 1/2 x t x△Q ** (右侧、两曲线之间、 覆盖损失交易的三角形)。混淆底边 -- 给收入用旧数量,或在 DWL 底边用旧数量 -- 是 C 部分最常见的失误。 AskSia Library . ECB1101 · 双语 Bilingual
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必会画图与标注（这是最稳的分）
- 坐标轴：Price($) 纵轴，Quantity 横轴；曲线命名 D、S；原均衡点虚线落轴。[14]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdf(a) Find P* and Q*, and draw the labelled diagram. [5] (b) The government imposes a $10 per-unit tax. Find Pb, Ps and the new quantity, and shade tax revenue and DWL on your graph. [8] (c) Calculate tax revenue and deadweight loss. [4] (d) In one sentence, explain why the DWL arises. [3] (a) 求 P* 与Q*,并画出带标注的图。[5] (b)政府征收一项$10 的从量税。求 Pb、Ps 与新数量,并在图上对税收收入 和 DWL 着色。[8](c)计算税收收入与无谓损失。[4](d)用一句话解释 DWL 为何产生。[3] WORKED SOLUTION 1 (a) Equilibrium. 60 - P = P -+ 60 = 2P - P* = 30; Q* = 30. ** (a) 均衡 。** 60 -P =P → 60= 2P→ ** P* = 30 **; Q* = ** 30 **. 2 (b) The wedge. Pb = Ps + 10 and 60 - Pb = Ps ++ 60 - (Ps + 10) = Ps - 50 = 2Ps - Ps = 25, Pb = 35. New Q = 60 - 35 = 25. ** (b)税楔 。** Pb = Ps + 10 且 60 - Pb = Ps → 60 -(Ps + 10) = Ps -> 50 = 2Ps -> *Ps = 25*, *Pb = 35 **. 新Q=60-35 =** 25 **。 3 (c) Revenue & DWL. Revenue = 10 × 25 = 250; DWL = 1/2 × 10 x(30-25) =1/2 ×10×5=25. ** (c) 收入与 DWL 。** 收入=10×25 =** 250 **; DWL = 1/2 × 10 x (30 - 25) = 1/2 x 10 × 5 = ** 25 **. 4 (d) Why DWL. The tax stops 5 mutually beneficial trades (Q 30-25) whose value to buyers exceeded their cost to sellers; that surplus is lost to everyone - it is not transferred, it simply disappears. Price ($) S $35 $25 D Quantity Buyers pay $35, sellers keep $25, Q falls 30 - 25. Amber rectangle = tax revenue (250); red triangle = deadweight loss (25). 买方付 ** $35 ** ,卖方留 ** $25 ** ,Q由 30→ 25 下 降。琥珀色矩形= 税收收入( ** 250 ** );红色三角形= 无谓损失( ** 25 ** )。 I tax revenue I deadweight loss AskSia Library · ECB1101 · 双语 Bilingual ** (d) 为何有 DWL 。** 税收阻止了5 笔互利交易(Q 30→25),这些交易对买方的价值超过对卖方的成本;那部 分剩余对 ** 所有人 ** 都损失了 -- 它没有被转移,而是直接 消失。 ★ What to LABEL for full marks (ECB1101 deducts for missing labels) 为拿满分该标注什么 (ECB1101 漏标会扣分) Axes: Price ($) on the vertical, Quantity on the horizontal. Both curves named D and S. Original equilibrium (P* = 30, Q* = 30) dotted to the axes. After the tax, mark Pb = 35 and Ps = 25 on the price axis and Q = 25 on the quantity axis. Shade and label the tax-revenue rectangle and the DWL triangle. State the tax wedge (the $10 vertical gap) explicitly - that gap is the whole story. ** 坐标轴 :** 纵轴为价格($),横轴为数量 。** 两条曲线 ** 分别标 D 和 S 。** 原均衡 ** (P *= 30,Q *= 30)用虚线连到坐 标轴。征税后,在价格轴上标出 ** Pb = 35 ** 和 ** Ps = 25 ** ,在数量轴上标出 ** Q= 25 **。** 阴影并标注 ** 税收收 入矩形和 DWL 三角形。明确写出 ** 税楔(tax wedge) ** (那$10的垂直缺口) -- 这个缺口就是全部要点。 ! The tax-revenue area is a rectangle, the DWL is a triangle 税收面积是矩形,DWL 是三角形 Tax revenue = t x new Q (a rectangle, height = the wedge, base = the smaller quantity). DWL = 1/2 x t x AQ (the triangle to the right, between the curves, over the lost trades). Mixing the bases - using the old quantity for revenue or the old quantity in the DWL base - is the most common Section-C slip. 税收收入= ** t x 新 Q ** (一个矩形,高=税楔,底=较小的数量)。DWL= ** 1/2 x t x△Q ** (右侧、两曲线之间、 覆盖损失交易的三角形)。混淆底边 -- 给收入用旧数量,或在 DWL 底边用旧数量 -- 是 C 部分最常见的失误。 AskSia Library . ECB1101 · 双语 Bilingual
- 征税后必须标：$P_b$、$P_s$、新 $Q$；涂并标注：税收收入矩形 + DWL 三角形；明确写出税楔就是那条垂直缺口。[14]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdf(a) Find P* and Q*, and draw the labelled diagram. [5] (b) The government imposes a $10 per-unit tax. Find Pb, Ps and the new quantity, and shade tax revenue and DWL on your graph. [8] (c) Calculate tax revenue and deadweight loss. [4] (d) In one sentence, explain why the DWL arises. [3] (a) 求 P* 与Q*,并画出带标注的图。[5] (b)政府征收一项$10 的从量税。求 Pb、Ps 与新数量,并在图上对税收收入 和 DWL 着色。[8](c)计算税收收入与无谓损失。[4](d)用一句话解释 DWL 为何产生。[3] WORKED SOLUTION 1 (a) Equilibrium. 60 - P = P -+ 60 = 2P - P* = 30; Q* = 30. ** (a) 均衡 。** 60 -P =P → 60= 2P→ ** P* = 30 **; Q* = ** 30 **. 2 (b) The wedge. Pb = Ps + 10 and 60 - Pb = Ps ++ 60 - (Ps + 10) = Ps - 50 = 2Ps - Ps = 25, Pb = 35. New Q = 60 - 35 = 25. ** (b)税楔 。** Pb = Ps + 10 且 60 - Pb = Ps → 60 -(Ps + 10) = Ps -> 50 = 2Ps -> *Ps = 25*, *Pb = 35 **. 新Q=60-35 =** 25 **。 3 (c) Revenue & DWL. Revenue = 10 × 25 = 250; DWL = 1/2 × 10 x(30-25) =1/2 ×10×5=25. ** (c) 收入与 DWL 。** 收入=10×25 =** 250 **; DWL = 1/2 × 10 x (30 - 25) = 1/2 x 10 × 5 = ** 25 **. 4 (d) Why DWL. The tax stops 5 mutually beneficial trades (Q 30-25) whose value to buyers exceeded their cost to sellers; that surplus is lost to everyone - it is not transferred, it simply disappears. Price ($) S $35 $25 D Quantity Buyers pay $35, sellers keep $25, Q falls 30 - 25. Amber rectangle = tax revenue (250); red triangle = deadweight loss (25). 买方付 ** $35 ** ,卖方留 ** $25 ** ,Q由 30→ 25 下 降。琥珀色矩形= 税收收入( ** 250 ** );红色三角形= 无谓损失( ** 25 ** )。 I tax revenue I deadweight loss AskSia Library · ECB1101 · 双语 Bilingual ** (d) 为何有 DWL 。** 税收阻止了5 笔互利交易(Q 30→25),这些交易对买方的价值超过对卖方的成本;那部 分剩余对 ** 所有人 ** 都损失了 -- 它没有被转移,而是直接 消失。 ★ What to LABEL for full marks (ECB1101 deducts for missing labels) 为拿满分该标注什么 (ECB1101 漏标会扣分) Axes: Price ($) on the vertical, Quantity on the horizontal. Both curves named D and S. Original equilibrium (P* = 30, Q* = 30) dotted to the axes. After the tax, mark Pb = 35 and Ps = 25 on the price axis and Q = 25 on the quantity axis. Shade and label the tax-revenue rectangle and the DWL triangle. State the tax wedge (the $10 vertical gap) explicitly - that gap is the whole story. ** 坐标轴 :** 纵轴为价格($),横轴为数量 。** 两条曲线 ** 分别标 D 和 S 。** 原均衡 ** (P *= 30,Q *= 30)用虚线连到坐 标轴。征税后,在价格轴上标出 ** Pb = 35 ** 和 ** Ps = 25 ** ,在数量轴上标出 ** Q= 25 **。** 阴影并标注 ** 税收收 入矩形和 DWL 三角形。明确写出 ** 税楔(tax wedge) ** (那$10的垂直缺口) -- 这个缺口就是全部要点。 ! The tax-revenue area is a rectangle, the DWL is a triangle 税收面积是矩形,DWL 是三角形 Tax revenue = t x new Q (a rectangle, height = the wedge, base = the smaller quantity). DWL = 1/2 x t x AQ (the triangle to the right, between the curves, over the lost trades). Mixing the bases - using the old quantity for revenue or the old quantity in the DWL base - is the most common Section-C slip. 税收收入= ** t x 新 Q ** (一个矩形,高=税楔,底=较小的数量)。DWL= ** 1/2 x t x△Q ** (右侧、两曲线之间、 覆盖损失交易的三角形)。混淆底边 -- 给收入用旧数量,或在 DWL 底边用旧数量 -- 是 C 部分最常见的失误。 AskSia Library . ECB1101 · 双语 Bilingual
- 最常见失误：
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Week 7（市场失灵）：外部性 Externality、矫正税 Pigouvian tax、公私物品
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负外部性（negative externality）必背一句话
- 负外部性意味着：$SMC > PMC$，市场会 过度生产。[4]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfi 4 . A corrective tax = the external effect 4 · 矫正税 = 外部效应 A negative externality means SMC > PMC: the market over-produces. The fix is a Pigouvian tax = the marginal external cost (SMC - PMC, not the price gap), which lifts private cost to social cost and restores the efficient Q. Positive externality - subsidy = external benefit. Public good = non-rival + non- excludable - free-riding. ** 负外部性(negative externality) ** 意味着 ** SMC > PMC **: 市场 ** 生产过多 **。 对策是 ** 庇古税 (Pigouvian tax)= 边际外部成本 ** (SMC - PMC,* 不是*价格差),它把私人成本抬升至社会成本,恢复 有效的Q。正外部性→补贴=外部收益。公共物品 = 非竞争性+非排他性→搭便车(free-riding)。 AskSia Library . ECB1101 · 双语 Bilingual ✓ 2 . Elasticity by the midpoint method 2 . 用中点法(midpoint method)算弹性 ECB1101's default is the midpoint (arc) method: divide each %-change by the average of the two values. If demand is inelastic (|E| < 1), raise price to raise revenue; if elastic, cut it; TR peaks at |E| = 1. On a tax, the less-elastic side bears more - it cannot walk away. ECB1101 默认用 ** 中点法(arc method) **: 每个百分 比变化除以两值的 ** 平均 **。 若需求 ** 缺乏弹性 ** ([E]<1), ** 提价 ** 可增收入;若 ** 富有弹性 ** ,则 降价;TR在 | == 1时达到峰值。对于税收, ** 弹性 较小的一方承担更多 **-- 它无处可逃。 § 3 . P = MC competition / MR = MC monopoly 3 . 完全竞争 P = MC / 垄断 MR = MC A price taker has P = MR, so produces where P = MC; shut down if P < AVC; long run, free entry drives P to min ATC and profit to zero. A monopolist sets MR = MC for the quantity, then reads price off demand (MR = a - 2bQ, twice the slope). Because P > MC it under- produces - deadweight loss. ** 价格接受者(price taker) ** P = MR,故在 ** P = MC ** 处生产 ;** P <AVC 则停业(shut down) **; 长 期下自由进入将 P 压到 ** min ATC **、 利润压到 ** 零 **。** 垄断者(monopolist) ** 令 ** MR = MC ** 定数 量,再从 ** 需求曲线 ** 读出价格 (MR = a-2bQ,斜 率两倍)。因P>MC 而生产不足→无谓损失。 ✓ 5 . The four market structures at a glance 5 · 四种市场结构一览 Perfect competition: many firms, identical good, no barriers, P = MR = MC, zero LR profit. Monopolistic competition: many, differentiated, P > MC, excess capacity, zero LR profit (P = ATC tangency). Oligopoly: few firms, interdependent, market power. Monopoly: one firm, barriers, P > MR = MC, DWL. Markup (P - MC) > 0 for the last three. ** 完全竞争 **: 企业众多、产品同质、无壁垒,P= MR = MC,长期零利润 。** 垄断竞争 **: 众多、差异 化,P> MC,过剩产能,长期零利润(P=ATC相 切) 。** 寡头(oligopoly) **: 少数企业、相互依存、有 市场势力 。** 垄断 **: 单一企业、有壁垒,P> MR = MC,有 DWL。后三者加成(P-MC)>0。 ★ 6 . ALWAYS draw and fully label every Section-C graph 6 · C 部分每张图都要画出并完整标注 Axes named, both curves drawn, equilibrium marked, shifts shown with arrows, and CS / PS / DWL shaded and labelled. ECB1101 deducts marks for unlabelled axes, curves and movements - these are the easiest marks in the paper and an arithmetic slip cannot cost them. Draw the diagram even when the question does not explicitly ask. 坐标轴要命名, ** 两条曲线 ** 都画出,标出 ** 均衡点 ** , ** 用箭头表示移位 ** ,CS / PS / DWL ** 阴影并 标注 **。 ECB1101 ** 对未标注的坐标轴、曲线和移动 扣分 **-- 这些是全卷最易得的分,算术失误也夺不 走它们。即便题目没明说,也要画图。 ~1. 3 min PER MARK - PACE IT 每分 -- 把握节奏 130 min FOR 100 MARKS 对应 100 分 40 mk SECTION C - LEAVE TIME TO DRAW C 部分 -- 留时间画图 HURDLE - JUST BANK THE MARKS 门槛 -- 把分收下即可 ! Pace it: 100 marks in 130 minutes 把握节奏:130 分钟拿 100 分
- 最优政策：庇古税（Pigouvian tax）= 边际外部成本：
- 正外部性：用补贴（subsidy）对应外部收益。[4]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfi 4 . A corrective tax = the external effect 4 · 矫正税 = 外部效应 A negative externality means SMC > PMC: the market over-produces. The fix is a Pigouvian tax = the marginal external cost (SMC - PMC, not the price gap), which lifts private cost to social cost and restores the efficient Q. Positive externality - subsidy = external benefit. Public good = non-rival + non- excludable - free-riding. ** 负外部性(negative externality) ** 意味着 ** SMC > PMC **: 市场 ** 生产过多 **。 对策是 ** 庇古税 (Pigouvian tax)= 边际外部成本 ** (SMC - PMC,* 不是*价格差),它把私人成本抬升至社会成本,恢复 有效的Q。正外部性→补贴=外部收益。公共物品 = 非竞争性+非排他性→搭便车(free-riding)。 AskSia Library . ECB1101 · 双语 Bilingual ✓ 2 . Elasticity by the midpoint method 2 . 用中点法(midpoint method)算弹性 ECB1101's default is the midpoint (arc) method: divide each %-change by the average of the two values. If demand is inelastic (|E| < 1), raise price to raise revenue; if elastic, cut it; TR peaks at |E| = 1. On a tax, the less-elastic side bears more - it cannot walk away. ECB1101 默认用 ** 中点法(arc method) **: 每个百分 比变化除以两值的 ** 平均 **。 若需求 ** 缺乏弹性 ** ([E]<1), ** 提价 ** 可增收入;若 ** 富有弹性 ** ,则 降价;TR在 | == 1时达到峰值。对于税收, ** 弹性 较小的一方承担更多 **-- 它无处可逃。 § 3 . P = MC competition / MR = MC monopoly 3 . 完全竞争 P = MC / 垄断 MR = MC A price taker has P = MR, so produces where P = MC; shut down if P < AVC; long run, free entry drives P to min ATC and profit to zero. A monopolist sets MR = MC for the quantity, then reads price off demand (MR = a - 2bQ, twice the slope). Because P > MC it under- produces - deadweight loss. ** 价格接受者(price taker) ** P = MR,故在 ** P = MC ** 处生产 ;** P <AVC 则停业(shut down) **; 长 期下自由进入将 P 压到 ** min ATC **、 利润压到 ** 零 **。** 垄断者(monopolist) ** 令 ** MR = MC ** 定数 量,再从 ** 需求曲线 ** 读出价格 (MR = a-2bQ,斜 率两倍)。因P>MC 而生产不足→无谓损失。 ✓ 5 . The four market structures at a glance 5 · 四种市场结构一览 Perfect competition: many firms, identical good, no barriers, P = MR = MC, zero LR profit. Monopolistic competition: many, differentiated, P > MC, excess capacity, zero LR profit (P = ATC tangency). Oligopoly: few firms, interdependent, market power. Monopoly: one firm, barriers, P > MR = MC, DWL. Markup (P - MC) > 0 for the last three. ** 完全竞争 **: 企业众多、产品同质、无壁垒,P= MR = MC,长期零利润 。** 垄断竞争 **: 众多、差异 化,P> MC,过剩产能,长期零利润(P=ATC相 切) 。** 寡头(oligopoly) **: 少数企业、相互依存、有 市场势力 。** 垄断 **: 单一企业、有壁垒,P> MR = MC,有 DWL。后三者加成(P-MC)>0。 ★ 6 . ALWAYS draw and fully label every Section-C graph 6 · C 部分每张图都要画出并完整标注 Axes named, both curves drawn, equilibrium marked, shifts shown with arrows, and CS / PS / DWL shaded and labelled. ECB1101 deducts marks for unlabelled axes, curves and movements - these are the easiest marks in the paper and an arithmetic slip cannot cost them. Draw the diagram even when the question does not explicitly ask. 坐标轴要命名, ** 两条曲线 ** 都画出,标出 ** 均衡点 ** , ** 用箭头表示移位 ** ,CS / PS / DWL ** 阴影并 标注 **。 ECB1101 ** 对未标注的坐标轴、曲线和移动 扣分 **-- 这些是全卷最易得的分,算术失误也夺不 走它们。即便题目没明说,也要画图。 ~1. 3 min PER MARK - PACE IT 每分 -- 把握节奏 130 min FOR 100 MARKS 对应 100 分 40 mk SECTION C - LEAVE TIME TO DRAW C 部分 -- 留时间画图 HURDLE - JUST BANK THE MARKS 门槛 -- 把分收下即可 ! Pace it: 100 marks in 130 minutes 把握节奏:130 分钟拿 100 分
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公共物品（public good）必背定义
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Weeks 8–11：企业与四种市场结构（Section C 另一大题：垄断）
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你必须背熟的两条企业规则（公式不多，但陷阱很致命）
- 完全竞争（price taker）：$P = MR$，所以产量在 $P=MC$ 处选；长期自由进入把 $P$ 压到 min ATC，长期利润为 0。[4]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfi 4 . A corrective tax = the external effect 4 · 矫正税 = 外部效应 A negative externality means SMC > PMC: the market over-produces. The fix is a Pigouvian tax = the marginal external cost (SMC - PMC, not the price gap), which lifts private cost to social cost and restores the efficient Q. Positive externality - subsidy = external benefit. Public good = non-rival + non- excludable - free-riding. ** 负外部性(negative externality) ** 意味着 ** SMC > PMC **: 市场 ** 生产过多 **。 对策是 ** 庇古税 (Pigouvian tax)= 边际外部成本 ** (SMC - PMC,* 不是*价格差),它把私人成本抬升至社会成本,恢复 有效的Q。正外部性→补贴=外部收益。公共物品 = 非竞争性+非排他性→搭便车(free-riding)。 AskSia Library . ECB1101 · 双语 Bilingual ✓ 2 . Elasticity by the midpoint method 2 . 用中点法(midpoint method)算弹性 ECB1101's default is the midpoint (arc) method: divide each %-change by the average of the two values. If demand is inelastic (|E| < 1), raise price to raise revenue; if elastic, cut it; TR peaks at |E| = 1. On a tax, the less-elastic side bears more - it cannot walk away. ECB1101 默认用 ** 中点法(arc method) **: 每个百分 比变化除以两值的 ** 平均 **。 若需求 ** 缺乏弹性 ** ([E]<1), ** 提价 ** 可增收入;若 ** 富有弹性 ** ,则 降价;TR在 | == 1时达到峰值。对于税收, ** 弹性 较小的一方承担更多 **-- 它无处可逃。 § 3 . P = MC competition / MR = MC monopoly 3 . 完全竞争 P = MC / 垄断 MR = MC A price taker has P = MR, so produces where P = MC; shut down if P < AVC; long run, free entry drives P to min ATC and profit to zero. A monopolist sets MR = MC for the quantity, then reads price off demand (MR = a - 2bQ, twice the slope). Because P > MC it under- produces - deadweight loss. ** 价格接受者(price taker) ** P = MR,故在 ** P = MC ** 处生产 ;** P <AVC 则停业(shut down) **; 长 期下自由进入将 P 压到 ** min ATC **、 利润压到 ** 零 **。** 垄断者(monopolist) ** 令 ** MR = MC ** 定数 量,再从 ** 需求曲线 ** 读出价格 (MR = a-2bQ,斜 率两倍)。因P>MC 而生产不足→无谓损失。 ✓ 5 . The four market structures at a glance 5 · 四种市场结构一览 Perfect competition: many firms, identical good, no barriers, P = MR = MC, zero LR profit. Monopolistic competition: many, differentiated, P > MC, excess capacity, zero LR profit (P = ATC tangency). Oligopoly: few firms, interdependent, market power. Monopoly: one firm, barriers, P > MR = MC, DWL. Markup (P - MC) > 0 for the last three. ** 完全竞争 **: 企业众多、产品同质、无壁垒,P= MR = MC,长期零利润 。** 垄断竞争 **: 众多、差异 化,P> MC,过剩产能,长期零利润(P=ATC相 切) 。** 寡头(oligopoly) **: 少数企业、相互依存、有 市场势力 。** 垄断 **: 单一企业、有壁垒,P> MR = MC,有 DWL。后三者加成(P-MC)>0。 ★ 6 . ALWAYS draw and fully label every Section-C graph 6 · C 部分每张图都要画出并完整标注 Axes named, both curves drawn, equilibrium marked, shifts shown with arrows, and CS / PS / DWL shaded and labelled. ECB1101 deducts marks for unlabelled axes, curves and movements - these are the easiest marks in the paper and an arithmetic slip cannot cost them. Draw the diagram even when the question does not explicitly ask. 坐标轴要命名, ** 两条曲线 ** 都画出,标出 ** 均衡点 ** , ** 用箭头表示移位 ** ,CS / PS / DWL ** 阴影并 标注 **。 ECB1101 ** 对未标注的坐标轴、曲线和移动 扣分 **-- 这些是全卷最易得的分,算术失误也夺不 走它们。即便题目没明说,也要画图。 ~1. 3 min PER MARK - PACE IT 每分 -- 把握节奏 130 min FOR 100 MARKS 对应 100 分 40 mk SECTION C - LEAVE TIME TO DRAW C 部分 -- 留时间画图 HURDLE - JUST BANK THE MARKS 门槛 -- 把分收下即可 ! Pace it: 100 marks in 130 minutes 把握节奏:130 分钟拿 100 分
- 垄断（monopolist）：
- 先用 $MR=MC$ 决定数量 $Q_m$
- 再回到需求曲线读价格 $P_m$（最常见错误：直接从 MR 读价格）。[6]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfI deadweight loss of monopoly AskSia Library · ECB1101 · 双语 Bilingual ** (c) 有效产量与 DWL 。** P = MC: 120-Q =20→ ** Qc=100 ** (在 P=$20处)。垄断者把产量限制在 50. DWL = 1/2 x (Pm - MC) x (Qc - Qm) = 1/2 x (70 - 20) x (100 - 50) = 1/2 x 50 x 50 = ** 1,250 ** - > ** $1. 25m **. Read-back: Pm = 70 > MC = 20 - price exceeds marginal cost, the signature of market power; the gap drives the welfare loss. ** 回读 :** Pm = 70 > MC= 20→价格超过边际成本,这 是 ** 市场势力 ** 的标志;该缺口驱动了福利损失。 ★ What to LABEL for full marks 为拿满分该标注什么 Axes (Price $, Quantity). Three curves: demand D = AR, the steeper MR (same intercept, twice the slope), and MC. Mark the MR = MC crossing to locate Qm = 50, then read up to demand for Pm = $70 (dotted guides). Mark Qc = 100 where D meets MC. Shade the DWL triangle between D and MC, from Qm to Qc. ** 坐标轴 ** (价格 $,数量) 。** 三条曲线 :** 需求 D= AR、更陡的 ** MR ** (同截距、斜率两倍)和 ** MC **。 标出 ** MR = MC ** 交点以确定 ** Qm= 50 ** ,再向上读到需求曲线得 ** Pm = $70 ** (虚线辅助)。标出D 与 MC 相交处 的 ** Qc = 100 **。 在 D与 MC 之间、从 Qm到 Qc, ** 阴影标出 DWL 三角形 **。 ! Quantity off MR = MC; price off the demand curve 产量由 MR= MC 决定;价格沿需求曲线读出 The single most common monopoly error is reading the price straight off MR. MR = MC locates only the quantity; the price is then read up to demand. And MR = a - 2bQ has twice the slope of demand - not the same line. A change in fixed cost would move profit but not Pm or Qm (MR and MC are unchanged). 垄断题最常见的单一错误是直接从 MR 读出价格 。** MR = MC 只定数量 **; 价格要 ** 向上读到需求曲线 **。 而 MR = a -2bQ 的斜率是需求的 ** 两倍 **-- 并非同一条线。固定成本的变化会改变利润,但 ** 不会 ** 改变Pm或Qm (MR 与 MC 不变)。 AskSia Library . ECB1101 · 双语 Bilingual EXAM MORNING - EXAM MORNING THE LAST HOUR If you remember nothing else 若别的都忘了,记住这些 Six reminders across the subject - read once, walk in, do it 全课六条提醒 -- 读一遍,进考场,照做 IN ONE LINE Set QD = Qs. Find the wedge. Shade the triangle. Label every axis, curve and shift. You have drilled this - now bank the easy marks. 令 Qp=Qs。求出楔子。给三角形着色。标注每条轴、每条曲线和每次移动。你已经反复练过 -- 现在把这些容易的分 稳稳收下。 THE CORE FORMULAS 1 . The chain set Qp = Qs - P*, Q *; CS / PS are triangle areas; a tax adds a wedge; DWL = 1/2 x tax x AQ 2 . Elasticity midpoint E = [4Q / Q] + [4P / P]; inelastic (|E| < 1) - raise price for more total revenue 3 . Firms competition P = MC; monopoly MR = MC then price off demand; MR = a - 2bQ; P > MC - DWL i 1 . The calculation chain is one method 1 · 计算链条本身就是一套方法 Almost every Section B/C question is the same chain: set QD = Qs for P*, Q *; CS / PS are triangle areas (1/2 × base x height, base = Q*); a tax drives a wedge Pb - Ps = t; and DWL = 1/2 x t x AQ. Reconcile: CS + PS + revenue + DWL must add back to the original surplus. 几乎每道 B/C 部分题目都是同一条链 :** 令 Qp= Qs ** 求P *、 Q *;** CS /PS 是三角形面积 ** (1/2 × 底 × 高,底=Q*);税收造成 ** 税楔 ** Pb -Ps = t;以及 ** DWL = 1/2 x t x △Q **。 核对:CS+ PS + 税收 +DWL 必须加总回原始剩余。[17]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfPRACTICE . SECTION C2 - PRACTICE BANK . SECTION C2 HYBRID . 20 MARKS . DRAW IT Graph-drawing hybrid - a monopoly publisher 画图综合题 -- 垄断出版商 MR = MC for quantity, price off demand; then profit, and the welfare loss MR = MC 定数量,价格取自需求;再算利润与福利损失 C2 GRAPH + CALCULATION + EXPLANATION 20 marks . monopoly hybrid A publisher is the sole seller of a textbook. It faces demand P = 120 - Q and has total cost TC = 20Q (so constant MC = 20); Q is in thousands. 某出版商是一本教科书的唯一卖方。它面对需求 P= 120-Q,总成本 TC= 20Q(故恒定 MC=20);Q 以千计。 (a) Write MR; find the profit-maximising Qm and Pm. [6] (b) Calculate profit. [4] (c) Find the efficient (competitive) output Qc where P = MC, and the deadweight loss. [6] (d) Draw D, MR, MC; mark (Qm, Pm) and shade the DWL. [4] (a)写出 MR;求利润最大化的Qm 与 Pm。[6](b)计算利润。[4](c)求 P=MC 处有效率(竞争)的产量 Qc,以及无谓 损失。[6](d)画出 D、MR、MC;标出(Qm,Pm)并对 DWL 着色。[4] WORKED SOLUTION 1 (a) MR and the optimum. For linear demand P = a - bQ, MR = a - 2bQ, so MR = 120 - 2Q. Set MR = MC: 120 - 2Q = 20 - 2Q = 100 -+ Qm = 50. Price off demand: Pm = 120 - 50 = $70 (never off MR). ** (a) MR 与最优 。** 对线性需求 P= a - bQ, MR = a - 2bQ,故 MR= ** 120 -2Q **。 令 MR = MC: 120-2Q = 20→ 2Q=100→ ** Qm = 50 **。 从 ** 需求 ** 读价:Pm = 120-50 =** $70 ** (绝不从 MR 读)。 2 (b) Profit. TR = 70 x 50 = 3,500; TC = 20 × 50 = 1,000. Profit = 3,500 - 1,000 = $2,500 (thousand) - $2. 5m. ** (b) 利润 。** TR = 70 ×50 = 3,500; TC= 20× 50= 1,000。利润= 3,500-1,000 =** $2,500 ** (千)→ ** $2. 5m **. 3 (c) Efficient output & DWL. P = MC: 120 - Q = 20 Qc = 100 (at P = $20). The monopolist restricts output to 50. DWL = 1/2 x (Pm - MC) x (Qc - Qm) = 1/2 x (70 - 20) x (100 - 50) = 1/2 x 50 x 50 = 1,250 - $1. 25m. Price ($) MC Pm Pc D MR Qm 0c Quantity The monopolist produces where MR = MC (Qm = 50) and prices off demand (Pm = $70). The efficient point is Qc = 100 at P = MC = $20. Red triangle = deadweight loss = 12 x 50 x 50 = 1,250. 垄断者在 ** MR = MC ** 处生产(Qm = 50),按需求曲线 定价(Pm=$70)。有效点是 P=MC=$20 处的Qc= 100。红色三角形= 无谓损失 = 1/2 × 50 × 50= ** 1,250 **.
- 线性需求：若 $P=a-bQ$，则 $MR=a-2bQ$（斜率是需求的两倍）。[4]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfi 4 . A corrective tax = the external effect 4 · 矫正税 = 外部效应 A negative externality means SMC > PMC: the market over-produces. The fix is a Pigouvian tax = the marginal external cost (SMC - PMC, not the price gap), which lifts private cost to social cost and restores the efficient Q. Positive externality - subsidy = external benefit. Public good = non-rival + non- excludable - free-riding. ** 负外部性(negative externality) ** 意味着 ** SMC > PMC **: 市场 ** 生产过多 **。 对策是 ** 庇古税 (Pigouvian tax)= 边际外部成本 ** (SMC - PMC,* 不是*价格差),它把私人成本抬升至社会成本,恢复 有效的Q。正外部性→补贴=外部收益。公共物品 = 非竞争性+非排他性→搭便车(free-riding)。 AskSia Library . ECB1101 · 双语 Bilingual ✓ 2 . Elasticity by the midpoint method 2 . 用中点法(midpoint method)算弹性 ECB1101's default is the midpoint (arc) method: divide each %-change by the average of the two values. If demand is inelastic (|E| < 1), raise price to raise revenue; if elastic, cut it; TR peaks at |E| = 1. On a tax, the less-elastic side bears more - it cannot walk away. ECB1101 默认用 ** 中点法(arc method) **: 每个百分 比变化除以两值的 ** 平均 **。 若需求 ** 缺乏弹性 ** ([E]<1), ** 提价 ** 可增收入;若 ** 富有弹性 ** ,则 降价;TR在 | == 1时达到峰值。对于税收, ** 弹性 较小的一方承担更多 **-- 它无处可逃。 § 3 . P = MC competition / MR = MC monopoly 3 . 完全竞争 P = MC / 垄断 MR = MC A price taker has P = MR, so produces where P = MC; shut down if P < AVC; long run, free entry drives P to min ATC and profit to zero. A monopolist sets MR = MC for the quantity, then reads price off demand (MR = a - 2bQ, twice the slope). Because P > MC it under- produces - deadweight loss. ** 价格接受者(price taker) ** P = MR,故在 ** P = MC ** 处生产 ;** P <AVC 则停业(shut down) **; 长 期下自由进入将 P 压到 ** min ATC **、 利润压到 ** 零 **。** 垄断者(monopolist) ** 令 ** MR = MC ** 定数 量,再从 ** 需求曲线 ** 读出价格 (MR = a-2bQ,斜 率两倍)。因P>MC 而生产不足→无谓损失。 ✓ 5 . The four market structures at a glance 5 · 四种市场结构一览 Perfect competition: many firms, identical good, no barriers, P = MR = MC, zero LR profit. Monopolistic competition: many, differentiated, P > MC, excess capacity, zero LR profit (P = ATC tangency). Oligopoly: few firms, interdependent, market power. Monopoly: one firm, barriers, P > MR = MC, DWL. Markup (P - MC) > 0 for the last three. ** 完全竞争 **: 企业众多、产品同质、无壁垒,P= MR = MC,长期零利润 。** 垄断竞争 **: 众多、差异 化,P> MC,过剩产能,长期零利润(P=ATC相 切) 。** 寡头(oligopoly) **: 少数企业、相互依存、有 市场势力 。** 垄断 **: 单一企业、有壁垒,P> MR = MC,有 DWL。后三者加成(P-MC)>0。 ★ 6 . ALWAYS draw and fully label every Section-C graph 6 · C 部分每张图都要画出并完整标注 Axes named, both curves drawn, equilibrium marked, shifts shown with arrows, and CS / PS / DWL shaded and labelled. ECB1101 deducts marks for unlabelled axes, curves and movements - these are the easiest marks in the paper and an arithmetic slip cannot cost them. Draw the diagram even when the question does not explicitly ask. 坐标轴要命名, ** 两条曲线 ** 都画出,标出 ** 均衡点 ** , ** 用箭头表示移位 ** ,CS / PS / DWL ** 阴影并 标注 **。 ECB1101 ** 对未标注的坐标轴、曲线和移动 扣分 **-- 这些是全卷最易得的分,算术失误也夺不 走它们。即便题目没明说,也要画图。 ~1. 3 min PER MARK - PACE IT 每分 -- 把握节奏 130 min FOR 100 MARKS 对应 100 分 40 mk SECTION C - LEAVE TIME TO DRAW C 部分 -- 留时间画图 HURDLE - JUST BANK THE MARKS 门槛 -- 把分收下即可 ! Pace it: 100 marks in 130 minutes 把握节奏:130 分钟拿 100 分[6]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfI deadweight loss of monopoly AskSia Library · ECB1101 · 双语 Bilingual ** (c) 有效产量与 DWL 。** P = MC: 120-Q =20→ ** Qc=100 ** (在 P=$20处)。垄断者把产量限制在 50. DWL = 1/2 x (Pm - MC) x (Qc - Qm) = 1/2 x (70 - 20) x (100 - 50) = 1/2 x 50 x 50 = ** 1,250 ** - > ** $1. 25m **. Read-back: Pm = 70 > MC = 20 - price exceeds marginal cost, the signature of market power; the gap drives the welfare loss. ** 回读 :** Pm = 70 > MC= 20→价格超过边际成本,这 是 ** 市场势力 ** 的标志;该缺口驱动了福利损失。 ★ What to LABEL for full marks 为拿满分该标注什么 Axes (Price $, Quantity). Three curves: demand D = AR, the steeper MR (same intercept, twice the slope), and MC. Mark the MR = MC crossing to locate Qm = 50, then read up to demand for Pm = $70 (dotted guides). Mark Qc = 100 where D meets MC. Shade the DWL triangle between D and MC, from Qm to Qc. ** 坐标轴 ** (价格 $,数量) 。** 三条曲线 :** 需求 D= AR、更陡的 ** MR ** (同截距、斜率两倍)和 ** MC **。 标出 ** MR = MC ** 交点以确定 ** Qm= 50 ** ,再向上读到需求曲线得 ** Pm = $70 ** (虚线辅助)。标出D 与 MC 相交处 的 ** Qc = 100 **。 在 D与 MC 之间、从 Qm到 Qc, ** 阴影标出 DWL 三角形 **。 ! Quantity off MR = MC; price off the demand curve 产量由 MR= MC 决定;价格沿需求曲线读出 The single most common monopoly error is reading the price straight off MR. MR = MC locates only the quantity; the price is then read up to demand. And MR = a - 2bQ has twice the slope of demand - not the same line. A change in fixed cost would move profit but not Pm or Qm (MR and MC are unchanged). 垄断题最常见的单一错误是直接从 MR 读出价格 。** MR = MC 只定数量 **; 价格要 ** 向上读到需求曲线 **。 而 MR = a -2bQ 的斜率是需求的 ** 两倍 **-- 并非同一条线。固定成本的变化会改变利润,但 ** 不会 ** 改变Pm或Qm (MR 与 MC 不变)。 AskSia Library . ECB1101 · 双语 Bilingual EXAM MORNING - EXAM MORNING THE LAST HOUR If you remember nothing else 若别的都忘了,记住这些 Six reminders across the subject - read once, walk in, do it 全课六条提醒 -- 读一遍,进考场,照做 IN ONE LINE Set QD = Qs. Find the wedge. Shade the triangle. Label every axis, curve and shift. You have drilled this - now bank the easy marks. 令 Qp=Qs。求出楔子。给三角形着色。标注每条轴、每条曲线和每次移动。你已经反复练过 -- 现在把这些容易的分 稳稳收下。 THE CORE FORMULAS 1 . The chain set Qp = Qs - P*, Q *; CS / PS are triangle areas; a tax adds a wedge; DWL = 1/2 x tax x AQ 2 . Elasticity midpoint E = [4Q / Q] + [4P / P]; inelastic (|E| < 1) - raise price for more total revenue 3 . Firms competition P = MC; monopoly MR = MC then price off demand; MR = a - 2bQ; P > MC - DWL i 1 . The calculation chain is one method 1 · 计算链条本身就是一套方法 Almost every Section B/C question is the same chain: set QD = Qs for P*, Q *; CS / PS are triangle areas (1/2 × base x height, base = Q*); a tax drives a wedge Pb - Ps = t; and DWL = 1/2 x t x AQ. Reconcile: CS + PS + revenue + DWL must add back to the original surplus. 几乎每道 B/C 部分题目都是同一条链 :** 令 Qp= Qs ** 求P *、 Q *;** CS /PS 是三角形面积 ** (1/2 × 底 × 高,底=Q*);税收造成 ** 税楔 ** Pb -Ps = t;以及 ** DWL = 1/2 x t x △Q **。 核对:CS+ PS + 税收 +DWL 必须加总回原始剩余。[17]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfPRACTICE . SECTION C2 - PRACTICE BANK . SECTION C2 HYBRID . 20 MARKS . DRAW IT Graph-drawing hybrid - a monopoly publisher 画图综合题 -- 垄断出版商 MR = MC for quantity, price off demand; then profit, and the welfare loss MR = MC 定数量,价格取自需求;再算利润与福利损失 C2 GRAPH + CALCULATION + EXPLANATION 20 marks . monopoly hybrid A publisher is the sole seller of a textbook. It faces demand P = 120 - Q and has total cost TC = 20Q (so constant MC = 20); Q is in thousands. 某出版商是一本教科书的唯一卖方。它面对需求 P= 120-Q,总成本 TC= 20Q(故恒定 MC=20);Q 以千计。 (a) Write MR; find the profit-maximising Qm and Pm. [6] (b) Calculate profit. [4] (c) Find the efficient (competitive) output Qc where P = MC, and the deadweight loss. [6] (d) Draw D, MR, MC; mark (Qm, Pm) and shade the DWL. [4] (a)写出 MR;求利润最大化的Qm 与 Pm。[6](b)计算利润。[4](c)求 P=MC 处有效率(竞争)的产量 Qc,以及无谓 损失。[6](d)画出 D、MR、MC;标出(Qm,Pm)并对 DWL 着色。[4] WORKED SOLUTION 1 (a) MR and the optimum. For linear demand P = a - bQ, MR = a - 2bQ, so MR = 120 - 2Q. Set MR = MC: 120 - 2Q = 20 - 2Q = 100 -+ Qm = 50. Price off demand: Pm = 120 - 50 = $70 (never off MR). ** (a) MR 与最优 。** 对线性需求 P= a - bQ, MR = a - 2bQ,故 MR= ** 120 -2Q **。 令 MR = MC: 120-2Q = 20→ 2Q=100→ ** Qm = 50 **。 从 ** 需求 ** 读价:Pm = 120-50 =** $70 ** (绝不从 MR 读)。 2 (b) Profit. TR = 70 x 50 = 3,500; TC = 20 × 50 = 1,000. Profit = 3,500 - 1,000 = $2,500 (thousand) - $2. 5m. ** (b) 利润 。** TR = 70 ×50 = 3,500; TC= 20× 50= 1,000。利润= 3,500-1,000 =** $2,500 ** (千)→ ** $2. 5m **. 3 (c) Efficient output & DWL. P = MC: 120 - Q = 20 Qc = 100 (at P = $20). The monopolist restricts output to 50. DWL = 1/2 x (Pm - MC) x (Qc - Qm) = 1/2 x (70 - 20) x (100 - 50) = 1/2 x 50 x 50 = 1,250 - $1. 25m. Price ($) MC Pm Pc D MR Qm 0c Quantity The monopolist produces where MR = MC (Qm = 50) and prices off demand (Pm = $70). The efficient point is Qc = 100 at P = MC = $20. Red triangle = deadweight loss = 12 x 50 x 50 = 1,250. 垄断者在 ** MR = MC ** 处生产(Qm = 50),按需求曲线 定价(Pm=$70)。有效点是 P=MC=$20 处的Qc= 100。红色三角形= 无谓损失 = 1/2 × 50 × 50= ** 1,250 **.
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Section C 垄断题标准模板（你要按这个顺序画）
- 画三条曲线：D(=AR)、更陡的 MR、以及 MC。[6]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfI deadweight loss of monopoly AskSia Library · ECB1101 · 双语 Bilingual ** (c) 有效产量与 DWL 。** P = MC: 120-Q =20→ ** Qc=100 ** (在 P=$20处)。垄断者把产量限制在 50. DWL = 1/2 x (Pm - MC) x (Qc - Qm) = 1/2 x (70 - 20) x (100 - 50) = 1/2 x 50 x 50 = ** 1,250 ** - > ** $1. 25m **. Read-back: Pm = 70 > MC = 20 - price exceeds marginal cost, the signature of market power; the gap drives the welfare loss. ** 回读 :** Pm = 70 > MC= 20→价格超过边际成本,这 是 ** 市场势力 ** 的标志;该缺口驱动了福利损失。 ★ What to LABEL for full marks 为拿满分该标注什么 Axes (Price $, Quantity). Three curves: demand D = AR, the steeper MR (same intercept, twice the slope), and MC. Mark the MR = MC crossing to locate Qm = 50, then read up to demand for Pm = $70 (dotted guides). Mark Qc = 100 where D meets MC. Shade the DWL triangle between D and MC, from Qm to Qc. ** 坐标轴 ** (价格 $,数量) 。** 三条曲线 :** 需求 D= AR、更陡的 ** MR ** (同截距、斜率两倍)和 ** MC **。 标出 ** MR = MC ** 交点以确定 ** Qm= 50 ** ,再向上读到需求曲线得 ** Pm = $70 ** (虚线辅助)。标出D 与 MC 相交处 的 ** Qc = 100 **。 在 D与 MC 之间、从 Qm到 Qc, ** 阴影标出 DWL 三角形 **。 ! Quantity off MR = MC; price off the demand curve 产量由 MR= MC 决定;价格沿需求曲线读出 The single most common monopoly error is reading the price straight off MR. MR = MC locates only the quantity; the price is then read up to demand. And MR = a - 2bQ has twice the slope of demand - not the same line. A change in fixed cost would move profit but not Pm or Qm (MR and MC are unchanged). 垄断题最常见的单一错误是直接从 MR 读出价格 。** MR = MC 只定数量 **; 价格要 ** 向上读到需求曲线 **。 而 MR = a -2bQ 的斜率是需求的 ** 两倍 **-- 并非同一条线。固定成本的变化会改变利润,但 ** 不会 ** 改变Pm或Qm (MR 与 MC 不变)。 AskSia Library . ECB1101 · 双语 Bilingual EXAM MORNING - EXAM MORNING THE LAST HOUR If you remember nothing else 若别的都忘了,记住这些 Six reminders across the subject - read once, walk in, do it 全课六条提醒 -- 读一遍,进考场,照做 IN ONE LINE Set QD = Qs. Find the wedge. Shade the triangle. Label every axis, curve and shift. You have drilled this - now bank the easy marks. 令 Qp=Qs。求出楔子。给三角形着色。标注每条轴、每条曲线和每次移动。你已经反复练过 -- 现在把这些容易的分 稳稳收下。 THE CORE FORMULAS 1 . The chain set Qp = Qs - P*, Q *; CS / PS are triangle areas; a tax adds a wedge; DWL = 1/2 x tax x AQ 2 . Elasticity midpoint E = [4Q / Q] + [4P / P]; inelastic (|E| < 1) - raise price for more total revenue 3 . Firms competition P = MC; monopoly MR = MC then price off demand; MR = a - 2bQ; P > MC - DWL i 1 . The calculation chain is one method 1 · 计算链条本身就是一套方法 Almost every Section B/C question is the same chain: set QD = Qs for P*, Q *; CS / PS are triangle areas (1/2 × base x height, base = Q*); a tax drives a wedge Pb - Ps = t; and DWL = 1/2 x t x AQ. Reconcile: CS + PS + revenue + DWL must add back to the original surplus. 几乎每道 B/C 部分题目都是同一条链 :** 令 Qp= Qs ** 求P *、 Q *;** CS /PS 是三角形面积 ** (1/2 × 底 × 高,底=Q*);税收造成 ** 税楔 ** Pb -Ps = t;以及 ** DWL = 1/2 x t x △Q **。 核对:CS+ PS + 税收 +DWL 必须加总回原始剩余。
- 用 $MR=MC$ 交点找 $Q_m$，再上读到 D 得 $P_m$（可画虚线辅助）。[6]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfI deadweight loss of monopoly AskSia Library · ECB1101 · 双语 Bilingual ** (c) 有效产量与 DWL 。** P = MC: 120-Q =20→ ** Qc=100 ** (在 P=$20处)。垄断者把产量限制在 50. DWL = 1/2 x (Pm - MC) x (Qc - Qm) = 1/2 x (70 - 20) x (100 - 50) = 1/2 x 50 x 50 = ** 1,250 ** - > ** $1. 25m **. Read-back: Pm = 70 > MC = 20 - price exceeds marginal cost, the signature of market power; the gap drives the welfare loss. ** 回读 :** Pm = 70 > MC= 20→价格超过边际成本,这 是 ** 市场势力 ** 的标志;该缺口驱动了福利损失。 ★ What to LABEL for full marks 为拿满分该标注什么 Axes (Price $, Quantity). Three curves: demand D = AR, the steeper MR (same intercept, twice the slope), and MC. Mark the MR = MC crossing to locate Qm = 50, then read up to demand for Pm = $70 (dotted guides). Mark Qc = 100 where D meets MC. Shade the DWL triangle between D and MC, from Qm to Qc. ** 坐标轴 ** (价格 $,数量) 。** 三条曲线 :** 需求 D= AR、更陡的 ** MR ** (同截距、斜率两倍)和 ** MC **。 标出 ** MR = MC ** 交点以确定 ** Qm= 50 ** ,再向上读到需求曲线得 ** Pm = $70 ** (虚线辅助)。标出D 与 MC 相交处 的 ** Qc = 100 **。 在 D与 MC 之间、从 Qm到 Qc, ** 阴影标出 DWL 三角形 **。 ! Quantity off MR = MC; price off the demand curve 产量由 MR= MC 决定;价格沿需求曲线读出 The single most common monopoly error is reading the price straight off MR. MR = MC locates only the quantity; the price is then read up to demand. And MR = a - 2bQ has twice the slope of demand - not the same line. A change in fixed cost would move profit but not Pm or Qm (MR and MC are unchanged). 垄断题最常见的单一错误是直接从 MR 读出价格 。** MR = MC 只定数量 **; 价格要 ** 向上读到需求曲线 **。 而 MR = a -2bQ 的斜率是需求的 ** 两倍 **-- 并非同一条线。固定成本的变化会改变利润,但 ** 不会 ** 改变Pm或Qm (MR 与 MC 不变)。 AskSia Library . ECB1101 · 双语 Bilingual EXAM MORNING - EXAM MORNING THE LAST HOUR If you remember nothing else 若别的都忘了,记住这些 Six reminders across the subject - read once, walk in, do it 全课六条提醒 -- 读一遍,进考场,照做 IN ONE LINE Set QD = Qs. Find the wedge. Shade the triangle. Label every axis, curve and shift. You have drilled this - now bank the easy marks. 令 Qp=Qs。求出楔子。给三角形着色。标注每条轴、每条曲线和每次移动。你已经反复练过 -- 现在把这些容易的分 稳稳收下。 THE CORE FORMULAS 1 . The chain set Qp = Qs - P*, Q *; CS / PS are triangle areas; a tax adds a wedge; DWL = 1/2 x tax x AQ 2 . Elasticity midpoint E = [4Q / Q] + [4P / P]; inelastic (|E| < 1) - raise price for more total revenue 3 . Firms competition P = MC; monopoly MR = MC then price off demand; MR = a - 2bQ; P > MC - DWL i 1 . The calculation chain is one method 1 · 计算链条本身就是一套方法 Almost every Section B/C question is the same chain: set QD = Qs for P*, Q *; CS / PS are triangle areas (1/2 × base x height, base = Q*); a tax drives a wedge Pb - Ps = t; and DWL = 1/2 x t x AQ. Reconcile: CS + PS + revenue + DWL must add back to the original surplus. 几乎每道 B/C 部分题目都是同一条链 :** 令 Qp= Qs ** 求P *、 Q *;** CS /PS 是三角形面积 ** (1/2 × 底 × 高,底=Q*);税收造成 ** 税楔 ** Pb -Ps = t;以及 ** DWL = 1/2 x t x △Q **。 核对:CS+ PS + 税收 +DWL 必须加总回原始剩余。
- 效率产量（竞争产量）：在 $P=MC$ 处找 $Q_c$。[6]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfI deadweight loss of monopoly AskSia Library · ECB1101 · 双语 Bilingual ** (c) 有效产量与 DWL 。** P = MC: 120-Q =20→ ** Qc=100 ** (在 P=$20处)。垄断者把产量限制在 50. DWL = 1/2 x (Pm - MC) x (Qc - Qm) = 1/2 x (70 - 20) x (100 - 50) = 1/2 x 50 x 50 = ** 1,250 ** - > ** $1. 25m **. Read-back: Pm = 70 > MC = 20 - price exceeds marginal cost, the signature of market power; the gap drives the welfare loss. ** 回读 :** Pm = 70 > MC= 20→价格超过边际成本,这 是 ** 市场势力 ** 的标志;该缺口驱动了福利损失。 ★ What to LABEL for full marks 为拿满分该标注什么 Axes (Price $, Quantity). Three curves: demand D = AR, the steeper MR (same intercept, twice the slope), and MC. Mark the MR = MC crossing to locate Qm = 50, then read up to demand for Pm = $70 (dotted guides). Mark Qc = 100 where D meets MC. Shade the DWL triangle between D and MC, from Qm to Qc. ** 坐标轴 ** (价格 $,数量) 。** 三条曲线 :** 需求 D= AR、更陡的 ** MR ** (同截距、斜率两倍)和 ** MC **。 标出 ** MR = MC ** 交点以确定 ** Qm= 50 ** ,再向上读到需求曲线得 ** Pm = $70 ** (虚线辅助)。标出D 与 MC 相交处 的 ** Qc = 100 **。 在 D与 MC 之间、从 Qm到 Qc, ** 阴影标出 DWL 三角形 **。 ! Quantity off MR = MC; price off the demand curve 产量由 MR= MC 决定;价格沿需求曲线读出 The single most common monopoly error is reading the price straight off MR. MR = MC locates only the quantity; the price is then read up to demand. And MR = a - 2bQ has twice the slope of demand - not the same line. A change in fixed cost would move profit but not Pm or Qm (MR and MC are unchanged). 垄断题最常见的单一错误是直接从 MR 读出价格 。** MR = MC 只定数量 **; 价格要 ** 向上读到需求曲线 **。 而 MR = a -2bQ 的斜率是需求的 ** 两倍 **-- 并非同一条线。固定成本的变化会改变利润,但 ** 不会 ** 改变Pm或Qm (MR 与 MC 不变)。 AskSia Library . ECB1101 · 双语 Bilingual EXAM MORNING - EXAM MORNING THE LAST HOUR If you remember nothing else 若别的都忘了,记住这些 Six reminders across the subject - read once, walk in, do it 全课六条提醒 -- 读一遍,进考场,照做 IN ONE LINE Set QD = Qs. Find the wedge. Shade the triangle. Label every axis, curve and shift. You have drilled this - now bank the easy marks. 令 Qp=Qs。求出楔子。给三角形着色。标注每条轴、每条曲线和每次移动。你已经反复练过 -- 现在把这些容易的分 稳稳收下。 THE CORE FORMULAS 1 . The chain set Qp = Qs - P*, Q *; CS / PS are triangle areas; a tax adds a wedge; DWL = 1/2 x tax x AQ 2 . Elasticity midpoint E = [4Q / Q] + [4P / P]; inelastic (|E| < 1) - raise price for more total revenue 3 . Firms competition P = MC; monopoly MR = MC then price off demand; MR = a - 2bQ; P > MC - DWL i 1 . The calculation chain is one method 1 · 计算链条本身就是一套方法 Almost every Section B/C question is the same chain: set QD = Qs for P*, Q *; CS / PS are triangle areas (1/2 × base x height, base = Q*); a tax drives a wedge Pb - Ps = t; and DWL = 1/2 x t x AQ. Reconcile: CS + PS + revenue + DWL must add back to the original surplus. 几乎每道 B/C 部分题目都是同一条链 :** 令 Qp= Qs ** 求P *、 Q *;** CS /PS 是三角形面积 ** (1/2 × 底 × 高,底=Q*);税收造成 ** 税楔 ** Pb -Ps = t;以及 ** DWL = 1/2 x t x △Q **。 核对:CS+ PS + 税收 +DWL 必须加总回原始剩余。[17]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfPRACTICE . SECTION C2 - PRACTICE BANK . SECTION C2 HYBRID . 20 MARKS . DRAW IT Graph-drawing hybrid - a monopoly publisher 画图综合题 -- 垄断出版商 MR = MC for quantity, price off demand; then profit, and the welfare loss MR = MC 定数量,价格取自需求;再算利润与福利损失 C2 GRAPH + CALCULATION + EXPLANATION 20 marks . monopoly hybrid A publisher is the sole seller of a textbook. It faces demand P = 120 - Q and has total cost TC = 20Q (so constant MC = 20); Q is in thousands. 某出版商是一本教科书的唯一卖方。它面对需求 P= 120-Q,总成本 TC= 20Q(故恒定 MC=20);Q 以千计。 (a) Write MR; find the profit-maximising Qm and Pm. [6] (b) Calculate profit. [4] (c) Find the efficient (competitive) output Qc where P = MC, and the deadweight loss. [6] (d) Draw D, MR, MC; mark (Qm, Pm) and shade the DWL. [4] (a)写出 MR;求利润最大化的Qm 与 Pm。[6](b)计算利润。[4](c)求 P=MC 处有效率(竞争)的产量 Qc,以及无谓 损失。[6](d)画出 D、MR、MC;标出(Qm,Pm)并对 DWL 着色。[4] WORKED SOLUTION 1 (a) MR and the optimum. For linear demand P = a - bQ, MR = a - 2bQ, so MR = 120 - 2Q. Set MR = MC: 120 - 2Q = 20 - 2Q = 100 -+ Qm = 50. Price off demand: Pm = 120 - 50 = $70 (never off MR). ** (a) MR 与最优 。** 对线性需求 P= a - bQ, MR = a - 2bQ,故 MR= ** 120 -2Q **。 令 MR = MC: 120-2Q = 20→ 2Q=100→ ** Qm = 50 **。 从 ** 需求 ** 读价:Pm = 120-50 =** $70 ** (绝不从 MR 读)。 2 (b) Profit. TR = 70 x 50 = 3,500; TC = 20 × 50 = 1,000. Profit = 3,500 - 1,000 = $2,500 (thousand) - $2. 5m. ** (b) 利润 。** TR = 70 ×50 = 3,500; TC= 20× 50= 1,000。利润= 3,500-1,000 =** $2,500 ** (千)→ ** $2. 5m **. 3 (c) Efficient output & DWL. P = MC: 120 - Q = 20 Qc = 100 (at P = $20). The monopolist restricts output to 50. DWL = 1/2 x (Pm - MC) x (Qc - Qm) = 1/2 x (70 - 20) x (100 - 50) = 1/2 x 50 x 50 = 1,250 - $1. 25m. Price ($) MC Pm Pc D MR Qm 0c Quantity The monopolist produces where MR = MC (Qm = 50) and prices off demand (Pm = $70). The efficient point is Qc = 100 at P = MC = $20. Red triangle = deadweight loss = 12 x 50 x 50 = 1,250. 垄断者在 ** MR = MC ** 处生产(Qm = 50),按需求曲线 定价(Pm=$70)。有效点是 P=MC=$20 处的Qc= 100。红色三角形= 无谓损失 = 1/2 × 50 × 50= ** 1,250 **.
- 无谓损失：在 D 与 MC 之间，从 $Q_m$ 到 $Q_c$ 涂三角形。[6]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfI deadweight loss of monopoly AskSia Library · ECB1101 · 双语 Bilingual ** (c) 有效产量与 DWL 。** P = MC: 120-Q =20→ ** Qc=100 ** (在 P=$20处)。垄断者把产量限制在 50. DWL = 1/2 x (Pm - MC) x (Qc - Qm) = 1/2 x (70 - 20) x (100 - 50) = 1/2 x 50 x 50 = ** 1,250 ** - > ** $1. 25m **. Read-back: Pm = 70 > MC = 20 - price exceeds marginal cost, the signature of market power; the gap drives the welfare loss. ** 回读 :** Pm = 70 > MC= 20→价格超过边际成本,这 是 ** 市场势力 ** 的标志;该缺口驱动了福利损失。 ★ What to LABEL for full marks 为拿满分该标注什么 Axes (Price $, Quantity). Three curves: demand D = AR, the steeper MR (same intercept, twice the slope), and MC. Mark the MR = MC crossing to locate Qm = 50, then read up to demand for Pm = $70 (dotted guides). Mark Qc = 100 where D meets MC. Shade the DWL triangle between D and MC, from Qm to Qc. ** 坐标轴 ** (价格 $,数量) 。** 三条曲线 :** 需求 D= AR、更陡的 ** MR ** (同截距、斜率两倍)和 ** MC **。 标出 ** MR = MC ** 交点以确定 ** Qm= 50 ** ,再向上读到需求曲线得 ** Pm = $70 ** (虚线辅助)。标出D 与 MC 相交处 的 ** Qc = 100 **。 在 D与 MC 之间、从 Qm到 Qc, ** 阴影标出 DWL 三角形 **。 ! Quantity off MR = MC; price off the demand curve 产量由 MR= MC 决定;价格沿需求曲线读出 The single most common monopoly error is reading the price straight off MR. MR = MC locates only the quantity; the price is then read up to demand. And MR = a - 2bQ has twice the slope of demand - not the same line. A change in fixed cost would move profit but not Pm or Qm (MR and MC are unchanged). 垄断题最常见的单一错误是直接从 MR 读出价格 。** MR = MC 只定数量 **; 价格要 ** 向上读到需求曲线 **。 而 MR = a -2bQ 的斜率是需求的 ** 两倍 **-- 并非同一条线。固定成本的变化会改变利润,但 ** 不会 ** 改变Pm或Qm (MR 与 MC 不变)。 AskSia Library . ECB1101 · 双语 Bilingual EXAM MORNING - EXAM MORNING THE LAST HOUR If you remember nothing else 若别的都忘了,记住这些 Six reminders across the subject - read once, walk in, do it 全课六条提醒 -- 读一遍,进考场,照做 IN ONE LINE Set QD = Qs. Find the wedge. Shade the triangle. Label every axis, curve and shift. You have drilled this - now bank the easy marks. 令 Qp=Qs。求出楔子。给三角形着色。标注每条轴、每条曲线和每次移动。你已经反复练过 -- 现在把这些容易的分 稳稳收下。 THE CORE FORMULAS 1 . The chain set Qp = Qs - P*, Q *; CS / PS are triangle areas; a tax adds a wedge; DWL = 1/2 x tax x AQ 2 . Elasticity midpoint E = [4Q / Q] + [4P / P]; inelastic (|E| < 1) - raise price for more total revenue 3 . Firms competition P = MC; monopoly MR = MC then price off demand; MR = a - 2bQ; P > MC - DWL i 1 . The calculation chain is one method 1 · 计算链条本身就是一套方法 Almost every Section B/C question is the same chain: set QD = Qs for P*, Q *; CS / PS are triangle areas (1/2 × base x height, base = Q*); a tax drives a wedge Pb - Ps = t; and DWL = 1/2 x t x AQ. Reconcile: CS + PS + revenue + DWL must add back to the original surplus. 几乎每道 B/C 部分题目都是同一条链 :** 令 Qp= Qs ** 求P *、 Q *;** CS /PS 是三角形面积 ** (1/2 × 底 × 高,底=Q*);税收造成 ** 税楔 ** Pb -Ps = t;以及 ** DWL = 1/2 x t x △Q **。 核对:CS+ PS + 税收 +DWL 必须加总回原始剩余。[17]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfPRACTICE . SECTION C2 - PRACTICE BANK . SECTION C2 HYBRID . 20 MARKS . DRAW IT Graph-drawing hybrid - a monopoly publisher 画图综合题 -- 垄断出版商 MR = MC for quantity, price off demand; then profit, and the welfare loss MR = MC 定数量,价格取自需求;再算利润与福利损失 C2 GRAPH + CALCULATION + EXPLANATION 20 marks . monopoly hybrid A publisher is the sole seller of a textbook. It faces demand P = 120 - Q and has total cost TC = 20Q (so constant MC = 20); Q is in thousands. 某出版商是一本教科书的唯一卖方。它面对需求 P= 120-Q,总成本 TC= 20Q(故恒定 MC=20);Q 以千计。 (a) Write MR; find the profit-maximising Qm and Pm. [6] (b) Calculate profit. [4] (c) Find the efficient (competitive) output Qc where P = MC, and the deadweight loss. [6] (d) Draw D, MR, MC; mark (Qm, Pm) and shade the DWL. [4] (a)写出 MR;求利润最大化的Qm 与 Pm。[6](b)计算利润。[4](c)求 P=MC 处有效率(竞争)的产量 Qc,以及无谓 损失。[6](d)画出 D、MR、MC;标出(Qm,Pm)并对 DWL 着色。[4] WORKED SOLUTION 1 (a) MR and the optimum. For linear demand P = a - bQ, MR = a - 2bQ, so MR = 120 - 2Q. Set MR = MC: 120 - 2Q = 20 - 2Q = 100 -+ Qm = 50. Price off demand: Pm = 120 - 50 = $70 (never off MR). ** (a) MR 与最优 。** 对线性需求 P= a - bQ, MR = a - 2bQ,故 MR= ** 120 -2Q **。 令 MR = MC: 120-2Q = 20→ 2Q=100→ ** Qm = 50 **。 从 ** 需求 ** 读价:Pm = 120-50 =** $70 ** (绝不从 MR 读)。 2 (b) Profit. TR = 70 x 50 = 3,500; TC = 20 × 50 = 1,000. Profit = 3,500 - 1,000 = $2,500 (thousand) - $2. 5m. ** (b) 利润 。** TR = 70 ×50 = 3,500; TC= 20× 50= 1,000。利润= 3,500-1,000 =** $2,500 ** (千)→ ** $2. 5m **. 3 (c) Efficient output & DWL. P = MC: 120 - Q = 20 Qc = 100 (at P = $20). The monopolist restricts output to 50. DWL = 1/2 x (Pm - MC) x (Qc - Qm) = 1/2 x (70 - 20) x (100 - 50) = 1/2 x 50 x 50 = 1,250 - $1. 25m. Price ($) MC Pm Pc D MR Qm 0c Quantity The monopolist produces where MR = MC (Qm = 50) and prices off demand (Pm = $70). The efficient point is Qc = 100 at P = MC = $20. Red triangle = deadweight loss = 12 x 50 x 50 = 1,250. 垄断者在 ** MR = MC ** 处生产(Qm = 50),按需求曲线 定价(Pm=$70)。有效点是 P=MC=$20 处的Qc= 100。红色三角形= 无谓损失 = 1/2 × 50 × 50= ** 1,250 **.
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垄断 DWL 计算公式（宝典给了标准算式）
- $$DWL=\frac12 \times (P_m-MC)\times (Q_c-Q_m)$$
- 宝典示例（$P=120-Q$，$MC=20$）：
- $MR=120-2Q$；$MR=MC \Rightarrow Q_m=50$；$P_m=70$
- $P=MC \Rightarrow Q_c=100$
- $DWL=\frac12(70-20)(100-50)=1250$（单位按题设）。[6]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfI deadweight loss of monopoly AskSia Library · ECB1101 · 双语 Bilingual ** (c) 有效产量与 DWL 。** P = MC: 120-Q =20→ ** Qc=100 ** (在 P=$20处)。垄断者把产量限制在 50. DWL = 1/2 x (Pm - MC) x (Qc - Qm) = 1/2 x (70 - 20) x (100 - 50) = 1/2 x 50 x 50 = ** 1,250 ** - > ** $1. 25m **. Read-back: Pm = 70 > MC = 20 - price exceeds marginal cost, the signature of market power; the gap drives the welfare loss. ** 回读 :** Pm = 70 > MC= 20→价格超过边际成本,这 是 ** 市场势力 ** 的标志;该缺口驱动了福利损失。 ★ What to LABEL for full marks 为拿满分该标注什么 Axes (Price $, Quantity). Three curves: demand D = AR, the steeper MR (same intercept, twice the slope), and MC. Mark the MR = MC crossing to locate Qm = 50, then read up to demand for Pm = $70 (dotted guides). Mark Qc = 100 where D meets MC. Shade the DWL triangle between D and MC, from Qm to Qc. ** 坐标轴 ** (价格 $,数量) 。** 三条曲线 :** 需求 D= AR、更陡的 ** MR ** (同截距、斜率两倍)和 ** MC **。 标出 ** MR = MC ** 交点以确定 ** Qm= 50 ** ,再向上读到需求曲线得 ** Pm = $70 ** (虚线辅助)。标出D 与 MC 相交处 的 ** Qc = 100 **。 在 D与 MC 之间、从 Qm到 Qc, ** 阴影标出 DWL 三角形 **。 ! Quantity off MR = MC; price off the demand curve 产量由 MR= MC 决定;价格沿需求曲线读出 The single most common monopoly error is reading the price straight off MR. MR = MC locates only the quantity; the price is then read up to demand. And MR = a - 2bQ has twice the slope of demand - not the same line. A change in fixed cost would move profit but not Pm or Qm (MR and MC are unchanged). 垄断题最常见的单一错误是直接从 MR 读出价格 。** MR = MC 只定数量 **; 价格要 ** 向上读到需求曲线 **。 而 MR = a -2bQ 的斜率是需求的 ** 两倍 **-- 并非同一条线。固定成本的变化会改变利润,但 ** 不会 ** 改变Pm或Qm (MR 与 MC 不变)。 AskSia Library . ECB1101 · 双语 Bilingual EXAM MORNING - EXAM MORNING THE LAST HOUR If you remember nothing else 若别的都忘了,记住这些 Six reminders across the subject - read once, walk in, do it 全课六条提醒 -- 读一遍,进考场,照做 IN ONE LINE Set QD = Qs. Find the wedge. Shade the triangle. Label every axis, curve and shift. You have drilled this - now bank the easy marks. 令 Qp=Qs。求出楔子。给三角形着色。标注每条轴、每条曲线和每次移动。你已经反复练过 -- 现在把这些容易的分 稳稳收下。 THE CORE FORMULAS 1 . The chain set Qp = Qs - P*, Q *; CS / PS are triangle areas; a tax adds a wedge; DWL = 1/2 x tax x AQ 2 . Elasticity midpoint E = [4Q / Q] + [4P / P]; inelastic (|E| < 1) - raise price for more total revenue 3 . Firms competition P = MC; monopoly MR = MC then price off demand; MR = a - 2bQ; P > MC - DWL i 1 . The calculation chain is one method 1 · 计算链条本身就是一套方法 Almost every Section B/C question is the same chain: set QD = Qs for P*, Q *; CS / PS are triangle areas (1/2 × base x height, base = Q*); a tax drives a wedge Pb - Ps = t; and DWL = 1/2 x t x AQ. Reconcile: CS + PS + revenue + DWL must add back to the original surplus. 几乎每道 B/C 部分题目都是同一条链 :** 令 Qp= Qs ** 求P *、 Q *;** CS /PS 是三角形面积 ** (1/2 × 底 × 高,底=Q*);税收造成 ** 税楔 ** Pb -Ps = t;以及 ** DWL = 1/2 x t x △Q **。 核对:CS+ PS + 税收 +DWL 必须加总回原始剩余。[17]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfPRACTICE . SECTION C2 - PRACTICE BANK . SECTION C2 HYBRID . 20 MARKS . DRAW IT Graph-drawing hybrid - a monopoly publisher 画图综合题 -- 垄断出版商 MR = MC for quantity, price off demand; then profit, and the welfare loss MR = MC 定数量,价格取自需求;再算利润与福利损失 C2 GRAPH + CALCULATION + EXPLANATION 20 marks . monopoly hybrid A publisher is the sole seller of a textbook. It faces demand P = 120 - Q and has total cost TC = 20Q (so constant MC = 20); Q is in thousands. 某出版商是一本教科书的唯一卖方。它面对需求 P= 120-Q,总成本 TC= 20Q(故恒定 MC=20);Q 以千计。 (a) Write MR; find the profit-maximising Qm and Pm. [6] (b) Calculate profit. [4] (c) Find the efficient (competitive) output Qc where P = MC, and the deadweight loss. [6] (d) Draw D, MR, MC; mark (Qm, Pm) and shade the DWL. [4] (a)写出 MR;求利润最大化的Qm 与 Pm。[6](b)计算利润。[4](c)求 P=MC 处有效率(竞争)的产量 Qc,以及无谓 损失。[6](d)画出 D、MR、MC;标出(Qm,Pm)并对 DWL 着色。[4] WORKED SOLUTION 1 (a) MR and the optimum. For linear demand P = a - bQ, MR = a - 2bQ, so MR = 120 - 2Q. Set MR = MC: 120 - 2Q = 20 - 2Q = 100 -+ Qm = 50. Price off demand: Pm = 120 - 50 = $70 (never off MR). ** (a) MR 与最优 。** 对线性需求 P= a - bQ, MR = a - 2bQ,故 MR= ** 120 -2Q **。 令 MR = MC: 120-2Q = 20→ 2Q=100→ ** Qm = 50 **。 从 ** 需求 ** 读价:Pm = 120-50 =** $70 ** (绝不从 MR 读)。 2 (b) Profit. TR = 70 x 50 = 3,500; TC = 20 × 50 = 1,000. Profit = 3,500 - 1,000 = $2,500 (thousand) - $2. 5m. ** (b) 利润 。** TR = 70 ×50 = 3,500; TC= 20× 50= 1,000。利润= 3,500-1,000 =** $2,500 ** (千)→ ** $2. 5m **. 3 (c) Efficient output & DWL. P = MC: 120 - Q = 20 Qc = 100 (at P = $20). The monopolist restricts output to 50. DWL = 1/2 x (Pm - MC) x (Qc - Qm) = 1/2 x (70 - 20) x (100 - 50) = 1/2 x 50 x 50 = 1,250 - $1. 25m. Price ($) MC Pm Pc D MR Qm 0c Quantity The monopolist produces where MR = MC (Qm = 50) and prices off demand (Pm = $70). The efficient point is Qc = 100 at P = MC = $20. Red triangle = deadweight loss = 12 x 50 x 50 = 1,250. 垄断者在 ** MR = MC ** 处生产(Qm = 50),按需求曲线 定价(Pm=$70)。有效点是 P=MC=$20 处的Qc= 100。红色三角形= 无谓损失 = 1/2 × 50 × 50= ** 1,250 **.
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四种市场结构（你至少要会“一句话区分 + 画图关键点”）
- Perfect competition：many firms，同质，无壁垒，$P=MR=MC$，长期零利润。[4]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfi 4 . A corrective tax = the external effect 4 · 矫正税 = 外部效应 A negative externality means SMC > PMC: the market over-produces. The fix is a Pigouvian tax = the marginal external cost (SMC - PMC, not the price gap), which lifts private cost to social cost and restores the efficient Q. Positive externality - subsidy = external benefit. Public good = non-rival + non- excludable - free-riding. ** 负外部性(negative externality) ** 意味着 ** SMC > PMC **: 市场 ** 生产过多 **。 对策是 ** 庇古税 (Pigouvian tax)= 边际外部成本 ** (SMC - PMC,* 不是*价格差),它把私人成本抬升至社会成本,恢复 有效的Q。正外部性→补贴=外部收益。公共物品 = 非竞争性+非排他性→搭便车(free-riding)。 AskSia Library . ECB1101 · 双语 Bilingual ✓ 2 . Elasticity by the midpoint method 2 . 用中点法(midpoint method)算弹性 ECB1101's default is the midpoint (arc) method: divide each %-change by the average of the two values. If demand is inelastic (|E| < 1), raise price to raise revenue; if elastic, cut it; TR peaks at |E| = 1. On a tax, the less-elastic side bears more - it cannot walk away. ECB1101 默认用 ** 中点法(arc method) **: 每个百分 比变化除以两值的 ** 平均 **。 若需求 ** 缺乏弹性 ** ([E]<1), ** 提价 ** 可增收入;若 ** 富有弹性 ** ,则 降价;TR在 | == 1时达到峰值。对于税收, ** 弹性 较小的一方承担更多 **-- 它无处可逃。 § 3 . P = MC competition / MR = MC monopoly 3 . 完全竞争 P = MC / 垄断 MR = MC A price taker has P = MR, so produces where P = MC; shut down if P < AVC; long run, free entry drives P to min ATC and profit to zero. A monopolist sets MR = MC for the quantity, then reads price off demand (MR = a - 2bQ, twice the slope). Because P > MC it under- produces - deadweight loss. ** 价格接受者(price taker) ** P = MR,故在 ** P = MC ** 处生产 ;** P <AVC 则停业(shut down) **; 长 期下自由进入将 P 压到 ** min ATC **、 利润压到 ** 零 **。** 垄断者(monopolist) ** 令 ** MR = MC ** 定数 量,再从 ** 需求曲线 ** 读出价格 (MR = a-2bQ,斜 率两倍)。因P>MC 而生产不足→无谓损失。 ✓ 5 . The four market structures at a glance 5 · 四种市场结构一览 Perfect competition: many firms, identical good, no barriers, P = MR = MC, zero LR profit. Monopolistic competition: many, differentiated, P > MC, excess capacity, zero LR profit (P = ATC tangency). Oligopoly: few firms, interdependent, market power. Monopoly: one firm, barriers, P > MR = MC, DWL. Markup (P - MC) > 0 for the last three. ** 完全竞争 **: 企业众多、产品同质、无壁垒,P= MR = MC,长期零利润 。** 垄断竞争 **: 众多、差异 化,P> MC,过剩产能,长期零利润(P=ATC相 切) 。** 寡头(oligopoly) **: 少数企业、相互依存、有 市场势力 。** 垄断 **: 单一企业、有壁垒,P> MR = MC,有 DWL。后三者加成(P-MC)>0。 ★ 6 . ALWAYS draw and fully label every Section-C graph 6 · C 部分每张图都要画出并完整标注 Axes named, both curves drawn, equilibrium marked, shifts shown with arrows, and CS / PS / DWL shaded and labelled. ECB1101 deducts marks for unlabelled axes, curves and movements - these are the easiest marks in the paper and an arithmetic slip cannot cost them. Draw the diagram even when the question does not explicitly ask. 坐标轴要命名, ** 两条曲线 ** 都画出,标出 ** 均衡点 ** , ** 用箭头表示移位 ** ,CS / PS / DWL ** 阴影并 标注 **。 ECB1101 ** 对未标注的坐标轴、曲线和移动 扣分 **-- 这些是全卷最易得的分,算术失误也夺不 走它们。即便题目没明说,也要画图。 ~1. 3 min PER MARK - PACE IT 每分 -- 把握节奏 130 min FOR 100 MARKS 对应 100 分 40 mk SECTION C - LEAVE TIME TO DRAW C 部分 -- 留时间画图 HURDLE - JUST BANK THE MARKS 门槛 -- 把分收下即可 ! Pace it: 100 marks in 130 minutes 把握节奏:130 分钟拿 100 分
- Monopolistic competition：many firms，差异化，$P>MC$，长期零利润（需求与 ATC 相切）。[4]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfi 4 . A corrective tax = the external effect 4 · 矫正税 = 外部效应 A negative externality means SMC > PMC: the market over-produces. The fix is a Pigouvian tax = the marginal external cost (SMC - PMC, not the price gap), which lifts private cost to social cost and restores the efficient Q. Positive externality - subsidy = external benefit. Public good = non-rival + non- excludable - free-riding. ** 负外部性(negative externality) ** 意味着 ** SMC > PMC **: 市场 ** 生产过多 **。 对策是 ** 庇古税 (Pigouvian tax)= 边际外部成本 ** (SMC - PMC,* 不是*价格差),它把私人成本抬升至社会成本,恢复 有效的Q。正外部性→补贴=外部收益。公共物品 = 非竞争性+非排他性→搭便车(free-riding)。 AskSia Library . ECB1101 · 双语 Bilingual ✓ 2 . Elasticity by the midpoint method 2 . 用中点法(midpoint method)算弹性 ECB1101's default is the midpoint (arc) method: divide each %-change by the average of the two values. If demand is inelastic (|E| < 1), raise price to raise revenue; if elastic, cut it; TR peaks at |E| = 1. On a tax, the less-elastic side bears more - it cannot walk away. ECB1101 默认用 ** 中点法(arc method) **: 每个百分 比变化除以两值的 ** 平均 **。 若需求 ** 缺乏弹性 ** ([E]<1), ** 提价 ** 可增收入;若 ** 富有弹性 ** ,则 降价;TR在 | == 1时达到峰值。对于税收, ** 弹性 较小的一方承担更多 **-- 它无处可逃。 § 3 . P = MC competition / MR = MC monopoly 3 . 完全竞争 P = MC / 垄断 MR = MC A price taker has P = MR, so produces where P = MC; shut down if P < AVC; long run, free entry drives P to min ATC and profit to zero. A monopolist sets MR = MC for the quantity, then reads price off demand (MR = a - 2bQ, twice the slope). Because P > MC it under- produces - deadweight loss. ** 价格接受者(price taker) ** P = MR,故在 ** P = MC ** 处生产 ;** P <AVC 则停业(shut down) **; 长 期下自由进入将 P 压到 ** min ATC **、 利润压到 ** 零 **。** 垄断者(monopolist) ** 令 ** MR = MC ** 定数 量,再从 ** 需求曲线 ** 读出价格 (MR = a-2bQ,斜 率两倍)。因P>MC 而生产不足→无谓损失。 ✓ 5 . The four market structures at a glance 5 · 四种市场结构一览 Perfect competition: many firms, identical good, no barriers, P = MR = MC, zero LR profit. Monopolistic competition: many, differentiated, P > MC, excess capacity, zero LR profit (P = ATC tangency). Oligopoly: few firms, interdependent, market power. Monopoly: one firm, barriers, P > MR = MC, DWL. Markup (P - MC) > 0 for the last three. ** 完全竞争 **: 企业众多、产品同质、无壁垒,P= MR = MC,长期零利润 。** 垄断竞争 **: 众多、差异 化,P> MC,过剩产能,长期零利润(P=ATC相 切) 。** 寡头(oligopoly) **: 少数企业、相互依存、有 市场势力 。** 垄断 **: 单一企业、有壁垒,P> MR = MC,有 DWL。后三者加成(P-MC)>0。 ★ 6 . ALWAYS draw and fully label every Section-C graph 6 · C 部分每张图都要画出并完整标注 Axes named, both curves drawn, equilibrium marked, shifts shown with arrows, and CS / PS / DWL shaded and labelled. ECB1101 deducts marks for unlabelled axes, curves and movements - these are the easiest marks in the paper and an arithmetic slip cannot cost them. Draw the diagram even when the question does not explicitly ask. 坐标轴要命名, ** 两条曲线 ** 都画出,标出 ** 均衡点 ** , ** 用箭头表示移位 ** ,CS / PS / DWL ** 阴影并 标注 **。 ECB1101 ** 对未标注的坐标轴、曲线和移动 扣分 **-- 这些是全卷最易得的分,算术失误也夺不 走它们。即便题目没明说,也要画图。 ~1. 3 min PER MARK - PACE IT 每分 -- 把握节奏 130 min FOR 100 MARKS 对应 100 分 40 mk SECTION C - LEAVE TIME TO DRAW C 部分 -- 留时间画图 HURDLE - JUST BANK THE MARKS 门槛 -- 把分收下即可 ! Pace it: 100 marks in 130 minutes 把握节奏:130 分钟拿 100 分[5]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfOligopoly a few large brewers dominate Part 2 - trace Sleek Sneakers from short run to long run 第2 部分––追踪 Sleek Sneakers 从短期到长期 1 (a) Short run, earning profit. Sleek faces its own downward demand. It maximises at MR = MC -+ q*, reads P* off demand above ATC, and earns profit = (P *- ATC)xq* - the shaded rectangle of Fig 11. 1. Exactly like a monopoly. ** (a) 短期,盈利 。** Sleek 面对自身向下倾斜的需求。它在 ** MR = MC ** 处最大化 → q*,在 ATC 之上从 ** 需求曲 线读出 P *** ,赚取利润 =(P *- ATC)xq *-- 即 ** 图 11. 1 ** 的阴影矩形。与垄断完全一样。 2 (b) Long run, profit competed away. Profits attract new sneaker brands. Each entrant pulls customers from Sleek, shifting Sleek's demand curve left until it is tangent to ATC: P falls to ATC, profit = 0 - the tangency of Fig 11. 2. ** (b)长期,利润被竞争掉 。** 利润吸引新运动鞋品牌进入。每个进入者从 Sleek 抢走顾客,使 ** Sleek 的需求曲线左 移 ** 直到与 ** ATC 相切 **: P 降至 ATC,利润=0 -- 即 ** 图 11. 2 ** 的切点。 3 (c) Stronger differentiation. A distinctive style makes demand steeper / less elastic (higher price, bigger markup); if it cannot be copied it becomes a barrier to entry, letting Sleek hold positive long- run profit (toward the monopoly end). ** (c)更强的差异化 。** 独特的款式使需求 ** 更陡/弹性更小 ** (价格更高、加成更大);若 ** 无法被模仿 ** ,它便成为 ** 进入壁垒(barrier to entry) ** ,让 Sleek 维持 ** 长期正利润 ** (偏向垄断一端)。 ✓ Section-C drawing sequence C 部分画图顺序 (1) SR: D, MR, MC, ATC; q* at MR = MC, P* up on D; shade profit. (2) Arrow: demand shifts left as firms enter. (3) LR: demand tangent to ATC, P = ATC, It = O. Label every axis, curve and shift arrow. ** (1) ** 短期(SR):画 D、MR、MC、ATC; q* 在 MR = MC处,P*沿D 向上取 ;** 阴影标出利润 **。** (2) ** 箭头:企业进入时需求 ** 左移 **。** (3) ** 长期(LR):需求 ** 与 ATC 相切 ** ,P = ATC,π=0。每条坐标轴、曲 线和移动箭头都要标注。 AskSia Library . ECB1101 · 双语 Bilingual GLOSSARY 1/ 3 - GLOSSARY 术语表 · EVERY TERM Every term, EN ←中文 每个术语,英←中 The whole ECB1101 vocabulary on three pages - grouped by topic, with one-line meanings 整套 ECB1101 词汇三页讲完 -- 按主题分组,附一句释义 IN ONE LINE Every examinable ECB1101 term in one place, English +> > with a one-line meaning. Screenshot it. The Chinese column is a translation aid - the exam itself is in English. 把每一个会考到的 ECB1101 术语集中一处,英文←中文,附一行释义。截图保存。中文列是翻译辅助 -- 考试本身是 英文的。 Term (EN) 中文 One-line meaning Foundations - scarcity, choice, the PPF Scarcity 稀缺 Unlimited wants meet finite resources, so we must choose.
- Oligopoly：few firms，相互依存，有市场势力。[4]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfi 4 . A corrective tax = the external effect 4 · 矫正税 = 外部效应 A negative externality means SMC > PMC: the market over-produces. The fix is a Pigouvian tax = the marginal external cost (SMC - PMC, not the price gap), which lifts private cost to social cost and restores the efficient Q. Positive externality - subsidy = external benefit. Public good = non-rival + non- excludable - free-riding. ** 负外部性(negative externality) ** 意味着 ** SMC > PMC **: 市场 ** 生产过多 **。 对策是 ** 庇古税 (Pigouvian tax)= 边际外部成本 ** (SMC - PMC,* 不是*价格差),它把私人成本抬升至社会成本,恢复 有效的Q。正外部性→补贴=外部收益。公共物品 = 非竞争性+非排他性→搭便车(free-riding)。 AskSia Library . ECB1101 · 双语 Bilingual ✓ 2 . Elasticity by the midpoint method 2 . 用中点法(midpoint method)算弹性 ECB1101's default is the midpoint (arc) method: divide each %-change by the average of the two values. If demand is inelastic (|E| < 1), raise price to raise revenue; if elastic, cut it; TR peaks at |E| = 1. On a tax, the less-elastic side bears more - it cannot walk away. ECB1101 默认用 ** 中点法(arc method) **: 每个百分 比变化除以两值的 ** 平均 **。 若需求 ** 缺乏弹性 ** ([E]<1), ** 提价 ** 可增收入;若 ** 富有弹性 ** ,则 降价;TR在 | == 1时达到峰值。对于税收, ** 弹性 较小的一方承担更多 **-- 它无处可逃。 § 3 . P = MC competition / MR = MC monopoly 3 . 完全竞争 P = MC / 垄断 MR = MC A price taker has P = MR, so produces where P = MC; shut down if P < AVC; long run, free entry drives P to min ATC and profit to zero. A monopolist sets MR = MC for the quantity, then reads price off demand (MR = a - 2bQ, twice the slope). Because P > MC it under- produces - deadweight loss. ** 价格接受者(price taker) ** P = MR,故在 ** P = MC ** 处生产 ;** P <AVC 则停业(shut down) **; 长 期下自由进入将 P 压到 ** min ATC **、 利润压到 ** 零 **。** 垄断者(monopolist) ** 令 ** MR = MC ** 定数 量,再从 ** 需求曲线 ** 读出价格 (MR = a-2bQ,斜 率两倍)。因P>MC 而生产不足→无谓损失。 ✓ 5 . The four market structures at a glance 5 · 四种市场结构一览 Perfect competition: many firms, identical good, no barriers, P = MR = MC, zero LR profit. Monopolistic competition: many, differentiated, P > MC, excess capacity, zero LR profit (P = ATC tangency). Oligopoly: few firms, interdependent, market power. Monopoly: one firm, barriers, P > MR = MC, DWL. Markup (P - MC) > 0 for the last three. ** 完全竞争 **: 企业众多、产品同质、无壁垒,P= MR = MC,长期零利润 。** 垄断竞争 **: 众多、差异 化,P> MC,过剩产能,长期零利润(P=ATC相 切) 。** 寡头(oligopoly) **: 少数企业、相互依存、有 市场势力 。** 垄断 **: 单一企业、有壁垒,P> MR = MC,有 DWL。后三者加成(P-MC)>0。 ★ 6 . ALWAYS draw and fully label every Section-C graph 6 · C 部分每张图都要画出并完整标注 Axes named, both curves drawn, equilibrium marked, shifts shown with arrows, and CS / PS / DWL shaded and labelled. ECB1101 deducts marks for unlabelled axes, curves and movements - these are the easiest marks in the paper and an arithmetic slip cannot cost them. Draw the diagram even when the question does not explicitly ask. 坐标轴要命名, ** 两条曲线 ** 都画出,标出 ** 均衡点 ** , ** 用箭头表示移位 ** ,CS / PS / DWL ** 阴影并 标注 **。 ECB1101 ** 对未标注的坐标轴、曲线和移动 扣分 **-- 这些是全卷最易得的分,算术失误也夺不 走它们。即便题目没明说,也要画图。 ~1. 3 min PER MARK - PACE IT 每分 -- 把握节奏 130 min FOR 100 MARKS 对应 100 分 40 mk SECTION C - LEAVE TIME TO DRAW C 部分 -- 留时间画图 HURDLE - JUST BANK THE MARKS 门槛 -- 把分收下即可 ! Pace it: 100 marks in 130 minutes 把握节奏:130 分钟拿 100 分[7]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfOne firm supplies the whole market most cheaply (large fixed cost, falling ATC). Monopolistic competition 垄断竞争 Many firms, differentiated products, free entry; P > MC but zero LR profit. AskSia Library . ECB1101 · 双语 Bilingual Term (EN) 中文 One-line meaning Product differentiation 产品差异化 Making your product distinct, giving each firm a little market power. Excess capacity 过剩产能 Monopolistic competitors produce below efficient scale (left of min ATC). Oligopoly 寡头垄断 A few interdependent firms; each one's choice affects the others. ✓ How to revise from this glossary 如何用这份术语表复习 Cover the right two columns and define each term from the English alone; then cover the English and recall it from the +X. Pay special attention to the pairs you can confuse - movement vs shift, CS vs PS, P = MC vs MR = MC, public good vs common resource, normal vs inferior. Knowing the contrast is what beats the Section-A distractors. 遮住右侧两列,仅凭英文定义每个术语;再遮住英文,凭 ** 中文 ** 回忆。特别留意 ** 易混淆的成对概念 **-- 移动 (movement)与移位(shift)、CS 与 PS、P =MC 与 MR= MC、公共物品(public good)与公共资源(common resource)、正常品(normal)与劣等品(inferior)。掌握其间的 ** 对比 ** 才是击败 A 部分干扰项的关键。 AskSia Library . ECB1101 · 双语 Bilingual PRACTICE . SECTION A - PRACTICE BANK DRILL TO EXAM STANDARD Drill the ECB1101 paper, with full solutions 演练 ECB1101 试卷,附完整解答 AskSia-authored, exam style - Section A MCQ, Section B calcs, Section C hybrids AskSia 原创、考试风格 -- A 部分选择题、B部分计算、C 部分综合题 IN ONE LINE Work each problem on paper first, then read the solution. The whole paper is one chain in disguise: set QD = Qs - elasticity - CS / PS - impose a policy - deadweight loss, plus the firm rules P = MC and MR = MC.
- Monopoly：one firm，有壁垒，$P>MR=MC$，有 DWL。[4]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfi 4 . A corrective tax = the external effect 4 · 矫正税 = 外部效应 A negative externality means SMC > PMC: the market over-produces. The fix is a Pigouvian tax = the marginal external cost (SMC - PMC, not the price gap), which lifts private cost to social cost and restores the efficient Q. Positive externality - subsidy = external benefit. Public good = non-rival + non- excludable - free-riding. ** 负外部性(negative externality) ** 意味着 ** SMC > PMC **: 市场 ** 生产过多 **。 对策是 ** 庇古税 (Pigouvian tax)= 边际外部成本 ** (SMC - PMC,* 不是*价格差),它把私人成本抬升至社会成本,恢复 有效的Q。正外部性→补贴=外部收益。公共物品 = 非竞争性+非排他性→搭便车(free-riding)。 AskSia Library . ECB1101 · 双语 Bilingual ✓ 2 . Elasticity by the midpoint method 2 . 用中点法(midpoint method)算弹性 ECB1101's default is the midpoint (arc) method: divide each %-change by the average of the two values. If demand is inelastic (|E| < 1), raise price to raise revenue; if elastic, cut it; TR peaks at |E| = 1. On a tax, the less-elastic side bears more - it cannot walk away. ECB1101 默认用 ** 中点法(arc method) **: 每个百分 比变化除以两值的 ** 平均 **。 若需求 ** 缺乏弹性 ** ([E]<1), ** 提价 ** 可增收入;若 ** 富有弹性 ** ,则 降价;TR在 | == 1时达到峰值。对于税收, ** 弹性 较小的一方承担更多 **-- 它无处可逃。 § 3 . P = MC competition / MR = MC monopoly 3 . 完全竞争 P = MC / 垄断 MR = MC A price taker has P = MR, so produces where P = MC; shut down if P < AVC; long run, free entry drives P to min ATC and profit to zero. A monopolist sets MR = MC for the quantity, then reads price off demand (MR = a - 2bQ, twice the slope). Because P > MC it under- produces - deadweight loss. ** 价格接受者(price taker) ** P = MR,故在 ** P = MC ** 处生产 ;** P <AVC 则停业(shut down) **; 长 期下自由进入将 P 压到 ** min ATC **、 利润压到 ** 零 **。** 垄断者(monopolist) ** 令 ** MR = MC ** 定数 量,再从 ** 需求曲线 ** 读出价格 (MR = a-2bQ,斜 率两倍)。因P>MC 而生产不足→无谓损失。 ✓ 5 . The four market structures at a glance 5 · 四种市场结构一览 Perfect competition: many firms, identical good, no barriers, P = MR = MC, zero LR profit. Monopolistic competition: many, differentiated, P > MC, excess capacity, zero LR profit (P = ATC tangency). Oligopoly: few firms, interdependent, market power. Monopoly: one firm, barriers, P > MR = MC, DWL. Markup (P - MC) > 0 for the last three. ** 完全竞争 **: 企业众多、产品同质、无壁垒,P= MR = MC,长期零利润 。** 垄断竞争 **: 众多、差异 化,P> MC,过剩产能,长期零利润(P=ATC相 切) 。** 寡头(oligopoly) **: 少数企业、相互依存、有 市场势力 。** 垄断 **: 单一企业、有壁垒,P> MR = MC,有 DWL。后三者加成(P-MC)>0。 ★ 6 . ALWAYS draw and fully label every Section-C graph 6 · C 部分每张图都要画出并完整标注 Axes named, both curves drawn, equilibrium marked, shifts shown with arrows, and CS / PS / DWL shaded and labelled. ECB1101 deducts marks for unlabelled axes, curves and movements - these are the easiest marks in the paper and an arithmetic slip cannot cost them. Draw the diagram even when the question does not explicitly ask. 坐标轴要命名, ** 两条曲线 ** 都画出,标出 ** 均衡点 ** , ** 用箭头表示移位 ** ,CS / PS / DWL ** 阴影并 标注 **。 ECB1101 ** 对未标注的坐标轴、曲线和移动 扣分 **-- 这些是全卷最易得的分,算术失误也夺不 走它们。即便题目没明说,也要画图。 ~1. 3 min PER MARK - PACE IT 每分 -- 把握节奏 130 min FOR 100 MARKS 对应 100 分 40 mk SECTION C - LEAVE TIME TO DRAW C 部分 -- 留时间画图 HURDLE - JUST BANK THE MARKS 门槛 -- 把分收下即可 ! Pace it: 100 marks in 130 minutes 把握节奏:130 分钟拿 100 分
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垄断竞争（monopolistic competition）“短期到长期”必会叙述
- 短期：像垄断一样在 $MR=MC$ 处定 $q^*$，从需求读 $P^*$；若 $P^*$ 在 ATC 上方则有利润（矩形）。[5]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfOligopoly a few large brewers dominate Part 2 - trace Sleek Sneakers from short run to long run 第2 部分––追踪 Sleek Sneakers 从短期到长期 1 (a) Short run, earning profit. Sleek faces its own downward demand. It maximises at MR = MC -+ q*, reads P* off demand above ATC, and earns profit = (P *- ATC)xq* - the shaded rectangle of Fig 11. 1. Exactly like a monopoly. ** (a) 短期,盈利 。** Sleek 面对自身向下倾斜的需求。它在 ** MR = MC ** 处最大化 → q*,在 ATC 之上从 ** 需求曲 线读出 P *** ,赚取利润 =(P *- ATC)xq *-- 即 ** 图 11. 1 ** 的阴影矩形。与垄断完全一样。 2 (b) Long run, profit competed away. Profits attract new sneaker brands. Each entrant pulls customers from Sleek, shifting Sleek's demand curve left until it is tangent to ATC: P falls to ATC, profit = 0 - the tangency of Fig 11. 2. ** (b)长期,利润被竞争掉 。** 利润吸引新运动鞋品牌进入。每个进入者从 Sleek 抢走顾客,使 ** Sleek 的需求曲线左 移 ** 直到与 ** ATC 相切 **: P 降至 ATC,利润=0 -- 即 ** 图 11. 2 ** 的切点。 3 (c) Stronger differentiation. A distinctive style makes demand steeper / less elastic (higher price, bigger markup); if it cannot be copied it becomes a barrier to entry, letting Sleek hold positive long- run profit (toward the monopoly end). ** (c)更强的差异化 。** 独特的款式使需求 ** 更陡/弹性更小 ** (价格更高、加成更大);若 ** 无法被模仿 ** ,它便成为 ** 进入壁垒(barrier to entry) ** ,让 Sleek 维持 ** 长期正利润 ** (偏向垄断一端)。 ✓ Section-C drawing sequence C 部分画图顺序 (1) SR: D, MR, MC, ATC; q* at MR = MC, P* up on D; shade profit. (2) Arrow: demand shifts left as firms enter. (3) LR: demand tangent to ATC, P = ATC, It = O. Label every axis, curve and shift arrow. ** (1) ** 短期(SR):画 D、MR、MC、ATC; q* 在 MR = MC处,P*沿D 向上取 ;** 阴影标出利润 **。** (2) ** 箭头:企业进入时需求 ** 左移 **。** (3) ** 长期(LR):需求 ** 与 ATC 相切 ** ,P = ATC,π=0。每条坐标轴、曲 线和移动箭头都要标注。 AskSia Library . ECB1101 · 双语 Bilingual GLOSSARY 1/ 3 - GLOSSARY 术语表 · EVERY TERM Every term, EN ←中文 每个术语,英←中 The whole ECB1101 vocabulary on three pages - grouped by topic, with one-line meanings 整套 ECB1101 词汇三页讲完 -- 按主题分组,附一句释义 IN ONE LINE Every examinable ECB1101 term in one place, English +> > with a one-line meaning. Screenshot it. The Chinese column is a translation aid - the exam itself is in English. 把每一个会考到的 ECB1101 术语集中一处,英文←中文,附一行释义。截图保存。中文列是翻译辅助 -- 考试本身是 英文的。 Term (EN) 中文 One-line meaning Foundations - scarcity, choice, the PPF Scarcity 稀缺 Unlimited wants meet finite resources, so we must choose.
- 长期：利润吸引进入 → 该企业需求曲线左移，直到与 ATC 相切 → $P=ATC$，利润为 0。[5]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfOligopoly a few large brewers dominate Part 2 - trace Sleek Sneakers from short run to long run 第2 部分––追踪 Sleek Sneakers 从短期到长期 1 (a) Short run, earning profit. Sleek faces its own downward demand. It maximises at MR = MC -+ q*, reads P* off demand above ATC, and earns profit = (P *- ATC)xq* - the shaded rectangle of Fig 11. 1. Exactly like a monopoly. ** (a) 短期,盈利 。** Sleek 面对自身向下倾斜的需求。它在 ** MR = MC ** 处最大化 → q*,在 ATC 之上从 ** 需求曲 线读出 P *** ,赚取利润 =(P *- ATC)xq *-- 即 ** 图 11. 1 ** 的阴影矩形。与垄断完全一样。 2 (b) Long run, profit competed away. Profits attract new sneaker brands. Each entrant pulls customers from Sleek, shifting Sleek's demand curve left until it is tangent to ATC: P falls to ATC, profit = 0 - the tangency of Fig 11. 2. ** (b)长期,利润被竞争掉 。** 利润吸引新运动鞋品牌进入。每个进入者从 Sleek 抢走顾客,使 ** Sleek 的需求曲线左 移 ** 直到与 ** ATC 相切 **: P 降至 ATC,利润=0 -- 即 ** 图 11. 2 ** 的切点。 3 (c) Stronger differentiation. A distinctive style makes demand steeper / less elastic (higher price, bigger markup); if it cannot be copied it becomes a barrier to entry, letting Sleek hold positive long- run profit (toward the monopoly end). ** (c)更强的差异化 。** 独特的款式使需求 ** 更陡/弹性更小 ** (价格更高、加成更大);若 ** 无法被模仿 ** ,它便成为 ** 进入壁垒(barrier to entry) ** ,让 Sleek 维持 ** 长期正利润 ** (偏向垄断一端)。 ✓ Section-C drawing sequence C 部分画图顺序 (1) SR: D, MR, MC, ATC; q* at MR = MC, P* up on D; shade profit. (2) Arrow: demand shifts left as firms enter. (3) LR: demand tangent to ATC, P = ATC, It = O. Label every axis, curve and shift arrow. ** (1) ** 短期(SR):画 D、MR、MC、ATC; q* 在 MR = MC处,P*沿D 向上取 ;** 阴影标出利润 **。** (2) ** 箭头:企业进入时需求 ** 左移 **。** (3) ** 长期(LR):需求 ** 与 ATC 相切 ** ,P = ATC,π=0。每条坐标轴、曲 线和移动箭头都要标注。 AskSia Library . ECB1101 · 双语 Bilingual GLOSSARY 1/ 3 - GLOSSARY 术语表 · EVERY TERM Every term, EN ←中文 每个术语,英←中 The whole ECB1101 vocabulary on three pages - grouped by topic, with one-line meanings 整套 ECB1101 词汇三页讲完 -- 按主题分组,附一句释义 IN ONE LINE Every examinable ECB1101 term in one place, English +> > with a one-line meaning. Screenshot it. The Chinese column is a translation aid - the exam itself is in English. 把每一个会考到的 ECB1101 术语集中一处,英文←中文,附一行释义。截图保存。中文列是翻译辅助 -- 考试本身是 英文的。 Term (EN) 中文 One-line meaning Foundations - scarcity, choice, the PPF Scarcity 稀缺 Unlimited wants meet finite resources, so we must choose.
- 差异化更强：需求更陡（更缺乏弹性）→ 更高价格、更大 markup；若不可复制会形成进入壁垒，可能长期正利润。[5]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfOligopoly a few large brewers dominate Part 2 - trace Sleek Sneakers from short run to long run 第2 部分––追踪 Sleek Sneakers 从短期到长期 1 (a) Short run, earning profit. Sleek faces its own downward demand. It maximises at MR = MC -+ q*, reads P* off demand above ATC, and earns profit = (P *- ATC)xq* - the shaded rectangle of Fig 11. 1. Exactly like a monopoly. ** (a) 短期,盈利 。** Sleek 面对自身向下倾斜的需求。它在 ** MR = MC ** 处最大化 → q*,在 ATC 之上从 ** 需求曲 线读出 P *** ,赚取利润 =(P *- ATC)xq *-- 即 ** 图 11. 1 ** 的阴影矩形。与垄断完全一样。 2 (b) Long run, profit competed away. Profits attract new sneaker brands. Each entrant pulls customers from Sleek, shifting Sleek's demand curve left until it is tangent to ATC: P falls to ATC, profit = 0 - the tangency of Fig 11. 2. ** (b)长期,利润被竞争掉 。** 利润吸引新运动鞋品牌进入。每个进入者从 Sleek 抢走顾客,使 ** Sleek 的需求曲线左 移 ** 直到与 ** ATC 相切 **: P 降至 ATC,利润=0 -- 即 ** 图 11. 2 ** 的切点。 3 (c) Stronger differentiation. A distinctive style makes demand steeper / less elastic (higher price, bigger markup); if it cannot be copied it becomes a barrier to entry, letting Sleek hold positive long- run profit (toward the monopoly end). ** (c)更强的差异化 。** 独特的款式使需求 ** 更陡/弹性更小 ** (价格更高、加成更大);若 ** 无法被模仿 ** ,它便成为 ** 进入壁垒(barrier to entry) ** ,让 Sleek 维持 ** 长期正利润 ** (偏向垄断一端)。 ✓ Section-C drawing sequence C 部分画图顺序 (1) SR: D, MR, MC, ATC; q* at MR = MC, P* up on D; shade profit. (2) Arrow: demand shifts left as firms enter. (3) LR: demand tangent to ATC, P = ATC, It = O. Label every axis, curve and shift arrow. ** (1) ** 短期(SR):画 D、MR、MC、ATC; q* 在 MR = MC处,P*沿D 向上取 ;** 阴影标出利润 **。** (2) ** 箭头:企业进入时需求 ** 左移 **。** (3) ** 长期(LR):需求 ** 与 ATC 相切 ** ,P = ATC,π=0。每条坐标轴、曲 线和移动箭头都要标注。 AskSia Library . ECB1101 · 双语 Bilingual GLOSSARY 1/ 3 - GLOSSARY 术语表 · EVERY TERM Every term, EN ←中文 每个术语,英←中 The whole ECB1101 vocabulary on three pages - grouped by topic, with one-line meanings 整套 ECB1101 词汇三页讲完 -- 按主题分组,附一句释义 IN ONE LINE Every examinable ECB1101 term in one place, English +> > with a one-line meaning. Screenshot it. The Chinese column is a translation aid - the exam itself is in English. 把每一个会考到的 ECB1101 术语集中一处,英文←中文,附一行释义。截图保存。中文列是翻译辅助 -- 考试本身是 英文的。 Term (EN) 中文 One-line meaning Foundations - scarcity, choice, the PPF Scarcity 稀缺 Unlimited wants meet finite resources, so we must choose.
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4）你现在最该怎么复习（按“40 分 Section C”倒推）
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复习优先级（从最值钱到次值钱）
- 第一优先：Section C 两大模型
- 税 + DWL（wedge、矩形税收、三角形 DWL、完整标注）[14]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdf(a) Find P* and Q*, and draw the labelled diagram. [5] (b) The government imposes a $10 per-unit tax. Find Pb, Ps and the new quantity, and shade tax revenue and DWL on your graph. [8] (c) Calculate tax revenue and deadweight loss. [4] (d) In one sentence, explain why the DWL arises. [3] (a) 求 P* 与Q*,并画出带标注的图。[5] (b)政府征收一项$10 的从量税。求 Pb、Ps 与新数量,并在图上对税收收入 和 DWL 着色。[8](c)计算税收收入与无谓损失。[4](d)用一句话解释 DWL 为何产生。[3] WORKED SOLUTION 1 (a) Equilibrium. 60 - P = P -+ 60 = 2P - P* = 30; Q* = 30. ** (a) 均衡 。** 60 -P =P → 60= 2P→ ** P* = 30 **; Q* = ** 30 **. 2 (b) The wedge. Pb = Ps + 10 and 60 - Pb = Ps ++ 60 - (Ps + 10) = Ps - 50 = 2Ps - Ps = 25, Pb = 35. New Q = 60 - 35 = 25. ** (b)税楔 。** Pb = Ps + 10 且 60 - Pb = Ps → 60 -(Ps + 10) = Ps -> 50 = 2Ps -> *Ps = 25*, *Pb = 35 **. 新Q=60-35 =** 25 **。 3 (c) Revenue & DWL. Revenue = 10 × 25 = 250; DWL = 1/2 × 10 x(30-25) =1/2 ×10×5=25. ** (c) 收入与 DWL 。** 收入=10×25 =** 250 **; DWL = 1/2 × 10 x (30 - 25) = 1/2 x 10 × 5 = ** 25 **. 4 (d) Why DWL. The tax stops 5 mutually beneficial trades (Q 30-25) whose value to buyers exceeded their cost to sellers; that surplus is lost to everyone - it is not transferred, it simply disappears. Price ($) S $35 $25 D Quantity Buyers pay $35, sellers keep $25, Q falls 30 - 25. Amber rectangle = tax revenue (250); red triangle = deadweight loss (25). 买方付 ** $35 ** ,卖方留 ** $25 ** ,Q由 30→ 25 下 降。琥珀色矩形= 税收收入( ** 250 ** );红色三角形= 无谓损失( ** 25 ** )。 I tax revenue I deadweight loss AskSia Library · ECB1101 · 双语 Bilingual ** (d) 为何有 DWL 。** 税收阻止了5 笔互利交易(Q 30→25),这些交易对买方的价值超过对卖方的成本;那部 分剩余对 ** 所有人 ** 都损失了 -- 它没有被转移,而是直接 消失。 ★ What to LABEL for full marks (ECB1101 deducts for missing labels) 为拿满分该标注什么 (ECB1101 漏标会扣分) Axes: Price ($) on the vertical, Quantity on the horizontal. Both curves named D and S. Original equilibrium (P* = 30, Q* = 30) dotted to the axes. After the tax, mark Pb = 35 and Ps = 25 on the price axis and Q = 25 on the quantity axis. Shade and label the tax-revenue rectangle and the DWL triangle. State the tax wedge (the $10 vertical gap) explicitly - that gap is the whole story. ** 坐标轴 :** 纵轴为价格($),横轴为数量 。** 两条曲线 ** 分别标 D 和 S 。** 原均衡 ** (P *= 30,Q *= 30)用虚线连到坐 标轴。征税后,在价格轴上标出 ** Pb = 35 ** 和 ** Ps = 25 ** ,在数量轴上标出 ** Q= 25 **。** 阴影并标注 ** 税收收 入矩形和 DWL 三角形。明确写出 ** 税楔(tax wedge) ** (那$10的垂直缺口) -- 这个缺口就是全部要点。 ! The tax-revenue area is a rectangle, the DWL is a triangle 税收面积是矩形,DWL 是三角形 Tax revenue = t x new Q (a rectangle, height = the wedge, base = the smaller quantity). DWL = 1/2 x t x AQ (the triangle to the right, between the curves, over the lost trades). Mixing the bases - using the old quantity for revenue or the old quantity in the DWL base - is the most common Section-C slip. 税收收入= ** t x 新 Q ** (一个矩形,高=税楔,底=较小的数量)。DWL= ** 1/2 x t x△Q ** (右侧、两曲线之间、 覆盖损失交易的三角形)。混淆底边 -- 给收入用旧数量,或在 DWL 底边用旧数量 -- 是 C 部分最常见的失误。 AskSia Library . ECB1101 · 双语 Bilingual
- 垄断（$MR=MC$ 定量、需求读价、$P=MC$ 找 $Q_c$、DWL 三角形）[6]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfI deadweight loss of monopoly AskSia Library · ECB1101 · 双语 Bilingual ** (c) 有效产量与 DWL 。** P = MC: 120-Q =20→ ** Qc=100 ** (在 P=$20处)。垄断者把产量限制在 50. DWL = 1/2 x (Pm - MC) x (Qc - Qm) = 1/2 x (70 - 20) x (100 - 50) = 1/2 x 50 x 50 = ** 1,250 ** - > ** $1. 25m **. Read-back: Pm = 70 > MC = 20 - price exceeds marginal cost, the signature of market power; the gap drives the welfare loss. ** 回读 :** Pm = 70 > MC= 20→价格超过边际成本,这 是 ** 市场势力 ** 的标志;该缺口驱动了福利损失。 ★ What to LABEL for full marks 为拿满分该标注什么 Axes (Price $, Quantity). Three curves: demand D = AR, the steeper MR (same intercept, twice the slope), and MC. Mark the MR = MC crossing to locate Qm = 50, then read up to demand for Pm = $70 (dotted guides). Mark Qc = 100 where D meets MC. Shade the DWL triangle between D and MC, from Qm to Qc. ** 坐标轴 ** (价格 $,数量) 。** 三条曲线 :** 需求 D= AR、更陡的 ** MR ** (同截距、斜率两倍)和 ** MC **。 标出 ** MR = MC ** 交点以确定 ** Qm= 50 ** ,再向上读到需求曲线得 ** Pm = $70 ** (虚线辅助)。标出D 与 MC 相交处 的 ** Qc = 100 **。 在 D与 MC 之间、从 Qm到 Qc, ** 阴影标出 DWL 三角形 **。 ! Quantity off MR = MC; price off the demand curve 产量由 MR= MC 决定;价格沿需求曲线读出 The single most common monopoly error is reading the price straight off MR. MR = MC locates only the quantity; the price is then read up to demand. And MR = a - 2bQ has twice the slope of demand - not the same line. A change in fixed cost would move profit but not Pm or Qm (MR and MC are unchanged). 垄断题最常见的单一错误是直接从 MR 读出价格 。** MR = MC 只定数量 **; 价格要 ** 向上读到需求曲线 **。 而 MR = a -2bQ 的斜率是需求的 ** 两倍 **-- 并非同一条线。固定成本的变化会改变利润,但 ** 不会 ** 改变Pm或Qm (MR 与 MC 不变)。 AskSia Library . ECB1101 · 双语 Bilingual EXAM MORNING - EXAM MORNING THE LAST HOUR If you remember nothing else 若别的都忘了,记住这些 Six reminders across the subject - read once, walk in, do it 全课六条提醒 -- 读一遍,进考场,照做 IN ONE LINE Set QD = Qs. Find the wedge. Shade the triangle. Label every axis, curve and shift. You have drilled this - now bank the easy marks. 令 Qp=Qs。求出楔子。给三角形着色。标注每条轴、每条曲线和每次移动。你已经反复练过 -- 现在把这些容易的分 稳稳收下。 THE CORE FORMULAS 1 . The chain set Qp = Qs - P*, Q *; CS / PS are triangle areas; a tax adds a wedge; DWL = 1/2 x tax x AQ 2 . Elasticity midpoint E = [4Q / Q] + [4P / P]; inelastic (|E| < 1) - raise price for more total revenue 3 . Firms competition P = MC; monopoly MR = MC then price off demand; MR = a - 2bQ; P > MC - DWL i 1 . The calculation chain is one method 1 · 计算链条本身就是一套方法 Almost every Section B/C question is the same chain: set QD = Qs for P*, Q *; CS / PS are triangle areas (1/2 × base x height, base = Q*); a tax drives a wedge Pb - Ps = t; and DWL = 1/2 x t x AQ. Reconcile: CS + PS + revenue + DWL must add back to the original surplus. 几乎每道 B/C 部分题目都是同一条链 :** 令 Qp= Qs ** 求P *、 Q *;** CS /PS 是三角形面积 ** (1/2 × 底 × 高,底=Q*);税收造成 ** 税楔 ** Pb -Ps = t;以及 ** DWL = 1/2 x t x △Q **。 核对:CS+ PS + 税收 +DWL 必须加总回原始剩余。[17]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfPRACTICE . SECTION C2 - PRACTICE BANK . SECTION C2 HYBRID . 20 MARKS . DRAW IT Graph-drawing hybrid - a monopoly publisher 画图综合题 -- 垄断出版商 MR = MC for quantity, price off demand; then profit, and the welfare loss MR = MC 定数量,价格取自需求;再算利润与福利损失 C2 GRAPH + CALCULATION + EXPLANATION 20 marks . monopoly hybrid A publisher is the sole seller of a textbook. It faces demand P = 120 - Q and has total cost TC = 20Q (so constant MC = 20); Q is in thousands. 某出版商是一本教科书的唯一卖方。它面对需求 P= 120-Q,总成本 TC= 20Q(故恒定 MC=20);Q 以千计。 (a) Write MR; find the profit-maximising Qm and Pm. [6] (b) Calculate profit. [4] (c) Find the efficient (competitive) output Qc where P = MC, and the deadweight loss. [6] (d) Draw D, MR, MC; mark (Qm, Pm) and shade the DWL. [4] (a)写出 MR;求利润最大化的Qm 与 Pm。[6](b)计算利润。[4](c)求 P=MC 处有效率(竞争)的产量 Qc,以及无谓 损失。[6](d)画出 D、MR、MC;标出(Qm,Pm)并对 DWL 着色。[4] WORKED SOLUTION 1 (a) MR and the optimum. For linear demand P = a - bQ, MR = a - 2bQ, so MR = 120 - 2Q. Set MR = MC: 120 - 2Q = 20 - 2Q = 100 -+ Qm = 50. Price off demand: Pm = 120 - 50 = $70 (never off MR). ** (a) MR 与最优 。** 对线性需求 P= a - bQ, MR = a - 2bQ,故 MR= ** 120 -2Q **。 令 MR = MC: 120-2Q = 20→ 2Q=100→ ** Qm = 50 **。 从 ** 需求 ** 读价:Pm = 120-50 =** $70 ** (绝不从 MR 读)。 2 (b) Profit. TR = 70 x 50 = 3,500; TC = 20 × 50 = 1,000. Profit = 3,500 - 1,000 = $2,500 (thousand) - $2. 5m. ** (b) 利润 。** TR = 70 ×50 = 3,500; TC= 20× 50= 1,000。利润= 3,500-1,000 =** $2,500 ** (千)→ ** $2. 5m **. 3 (c) Efficient output & DWL. P = MC: 120 - Q = 20 Qc = 100 (at P = $20). The monopolist restricts output to 50. DWL = 1/2 x (Pm - MC) x (Qc - Qm) = 1/2 x (70 - 20) x (100 - 50) = 1/2 x 50 x 50 = 1,250 - $1. 25m. Price ($) MC Pm Pc D MR Qm 0c Quantity The monopolist produces where MR = MC (Qm = 50) and prices off demand (Pm = $70). The efficient point is Qc = 100 at P = MC = $20. Red triangle = deadweight loss = 12 x 50 x 50 = 1,250. 垄断者在 ** MR = MC ** 处生产(Qm = 50),按需求曲线 定价(Pm=$70)。有效点是 P=MC=$20 处的Qc= 100。红色三角形= 无谓损失 = 1/2 × 50 × 50= ** 1,250 **.
- 第二优先：Week 3–5 基础链条
- 线性供需均衡、移动 vs 移位、CS/PS/TS 三角形面积、效率与 DWL。[10]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfEquilibrium: P* = $12, Q* = 72. The check - sub P* into the other curve and confirm the same Q - is free marks. 均衡:P *= $12, Q *= 72。检验––把 P*代入另一 条曲线、确认得到相同的 Q -- 是白送的分。 - Price ($) S $12 D Quantity The worked market: Qd=120-4P and Qs=6P cross at P *= $12, Q *= 72. The same picture underlies every later surplus, tax and welfare calculation. 已解市场:Qd=120-4P 与 Qs=6P 相交于 P *= $12, Q *= 72。后续所有剩余、税收和福利计算都以这张图为 基础。 i Reading the equations as a picture 把方程读成一幅图 Qd=120-4P hits the price axis at P=$30 (where Q=0) and the quantity axis at Q=120 (where P=0). Qs=6P starts at the origin. Sketching those intercepts before solving catches sign errors fast. Qd=120-4P 在 P=$30 处(Q=0)碰到价格轴,在 Q=120 处(P=0)碰到数量轴。Qs=6P 从原点出发。求 解前先草绘这些截距能快速抓出符号错误。 ! Demand vs quantity demanded; P-on-axis confusion 需求 vs 需求量;P 在纵轴的混淆 Two recurring slips: (1) Although we write Q as a function of P, economists draw P on the vertical axis - do the algebra in whichever form is given, then map to the graph. (2) Set quantities equal, never prices - demand and supply share the same market price, so it is Qd = Qs that pins down P *. 两个反复出现的失误:(1)虽然我们把 Q 写成 P的函数,但经济学家把 P 画在纵轴 -- 用给定的形式做代数,再映射到 图上。(2)令数量相等,绝不令价格相等 -- 供求共享同一个市场价格,所以是 Qd= Qs 钉住 P *。 AskSia Library . ECB1101 · 双语 Bilingual ★ Exam move - the equilibrium-first habit 考试技巧 -- 先求均衡的习惯 Whatever the policy to come - tax, subsidy, floor, ceiling - the first marks are always the free-market equilibrium: set Qd=Qs, get (P*, Q*), and label it on a clean, fully-labelled diagram (both axes, both curves, the crossing point). Everything in Weeks 4-6 is measured as a change from this point. 无论接下来是什么政策 -- 税、补贴、价格下限、价格上限 -- 头几分总是自由市场均衡:令 Qd=Qs,得(P*,Q*),并 在一张干净、完整标注的图上把它标出来(两条轴、两条曲线、交点)。第4-6周的一切都以从这一点起的变化来衡量。 AskSia Library . ECB1101 · 双语 Bilingual CH 4 . MIDPOINT PED - CHAPTER 4 . ELASTICITY THE CALC-HEAVY WEEK How much quantity responds - as a number 数量反应有多大 -- 用数字说话 Price, income and cross-price elasticity by the midpoint method 用中点法求价格、收入与交叉价格弹性 IN ONE LINE Elasticity turns a curve's slope into a unit-free number. ECB1101 computes it by the midpoint (arc) method: %AQ and %AP are each change * average, so the same number comes out whichever direction you move. |E| > 1 elastic, < 1 inelastic, = 1 unit-elastic. 弹性把曲线的斜率变成一个无单位的数字。ECB1101 用中点(弧)法(midpoint method)计算:%△Q 和 %△P 各为变化量 ÷ 平均值,所以无论朝哪个方向移动都得出同一个数。|||>1富有弹性,<1缺乏弹性,=1单位弹性。[12]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdf这些符号就是第3周的需求移动因素的数字化。某替代品价格上升使需求右移(EAB>0);某互补品价格上升使其左移 (EAB<O);收入提高使正常品需求右移(E1>0)。收入弹性<0是劣等品的标志 -- 所以“收入弹性总是正的”是错的。 - AskSia Library . ECB1101 · 双语 Bilingual ★ Exam move - the elasticity checklist 考试技巧 -- 弹性清单 (1) Identify which elasticity is asked - own-price, income, cross-price, or supply. (2) For every one, use the midpoint method: change + average, top and bottom. (3) For PED, take the absolute value and classify against 1, then apply the total-revenue rule. (4) For income / cross-price, the marks are in the sign: + or -, then name the good or relationship. Show every division - partial steps still earn marks. (1)辨明问的是哪种弹性 -- 自身价格、收入、交叉价格还是供给。(2)对每一种都用中点法:上下都是 变化÷平均。 (3)对 PED,取绝对值并与1比较分类,然后应用总收益法则。(4)对收入/交叉价格,分数在符号上:+或一,然后 说出商品或关系。把每次除法都写出来 -- 部分步骤仍能得分。 AskSia Library . ECB1101 · 双语 Bilingual CH 5 . SURPLUS - CHAPTER 5 . SURPLUS & MARKET EFFICIENCY EFFICIENCY Why the competitive market gets it right 竞争市场为何能达到最优 Consumer surplus, producer surplus and total surplus (TS) 消费者剩余(CS)、生产者剩余(PS)与社会总剩余(TS) IN ONE LINE Total surplus TS = CS + PS, and each piece is a triangle: CS is the area under demand above price, PS the area above supply below price. The competitive equilibrium Q* maximises TS; any other quantity wastes value - that wasted triangle is the deadweight loss. 社会总剩余 TS = CS+PS,每一块都是三角形:CS 是需求曲线下方、价格上方的面积,PS 是供给曲线上方、价格下 方的面积。竞争均衡的 Q*使 TS 最大化;任何其他数量都浪费价值 -- 那块被浪费的三角形就是无谓损失(DWL)。 A market does more than set a price - it creates value. Buyers pay less than the good is worth to them; sellers receive more than it cost them to supply. Add the two gains and you get total surplus (TS), the single number that measures how much a market benefits society. This chapter shows why the competitive equilibrium maximises TS - the result every later policy chapter measures against. 市场不只设定价格 -- 它还创造价值。买方支付的少于商品对他们的价值;卖方收到的多于其供给成本。把这两份所得相加, 就得到社会总剩余(TS),这个单一数字衡量市场让社会受益多少。本章说明为何竞争均衡使 TS 最大化 -- 这是往后每项政策 章节用来对照的结论。 ★ Why this chapter is the ruler for half the exam 为何本章是半张试卷的标尺 Surplus is the measuring stick every later topic uses. Taxes, price controls and externalities are all scored by how much total surplus they destroy - the deadweight loss. Get the three triangles automatic here and Chapter 6 becomes arithmetic. Quiz 2 (Week 7) opens with exactly this: CS, PS and TS read off a diagram. 剩余是往后每个主题都要用的量尺。税收、价格管制和外部性都按它们毁掉多少社会总剩余来评分 -- 即无谓损失。在 这里把三个三角形练到自动化,第6章就成了算术。测验 2(第7周)恰以此开场:从图上读出 CS、PS和 TS。 AskSia Library . ECB1101 · 双语 Bilingual Consumer surplus - what buyers gain 消费者剩余 -- 买方所得 Each buyer has a willingness to pay (WTP) - the height of the demand curve at that unit. They actually pay the market price. The difference is their gain. Summed over all units, consumer surplus is the area under demand and above price. 每个买方都有一个支付意愿(WTP) -- 即需求曲线在该单位 处的高度。他们实际支付市场价格。两者之差就是他们的所 得。对所有单位求和,消费者剩余就是需求曲线下方、价格 上方的面积。 Producer surplus - what sellers gain 生产者剩余 -- 卖方所得 Each seller has a willingness to sell (WTS) - their marginal cost, the height of the supply curve. They receive the market price; the gap is their gain. Summed, producer surplus is the area above supply and below price. 每个卖方都有一个出售意愿(WTS) -- 即其边际成本,也就 是供给曲线的高度。他们收到市场价格;差额就是他们的所 得。求和后,生产者剩余就是供给曲线上方、价格下方的面 积。[13]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdf市场(market)在需求量等于供给量的价格处达成均衡。商品的自身价格使你沿着曲线移动;其他任何因素都会使整条曲 线移动。钉牢这一区分和四种移动情形,你就掌握了 ECB1101。 This is Week 3 (Mankiw Ch 4). A market is buyers and sellers of a good interacting. Demand and supply is the engine of the whole subject: nearly every exam calculation begins by finding where the two curves cross, then layers a policy on top. Get the two curves, the difference between a shift and a movement, and the four comparative-static cases - and you own the model. 这是第 3周(Mankiw 第4章)。市场(market)是某商品的买方与卖方在互动。供给与需求是整个学科的引擎:几乎每道考试计 算都从找两条曲线的交点开始,再在其上叠加一项政策。掌握这两条曲线、移动(shift)与滑动(movement)的区别,以及四种 比较静态情形 -- 你就掌握了这个模型。 ★ How ECB1101 tests this ECB1101 如何考查这一点 Week 3 is the workhorse of Sections B and C. Expect: read a P-Q schedule and find (P*, Q*); classify a change as a movement along vs a shift of a curve; run comparative statics (given a shift, say what happens to P* and Q* - including the "ambiguous" case when both curves move); and solve linear D & S algebraically. Section C wants the diagram drawn and every shift arrowed. 第3 周是B、C 两部分的主力。预期会有:读 P-Q 表并求(P*,Q*);把一项变化归类为曲线的沿线滑动还是移动;做 比较静态(给定一次移动,说出 P*和Q*会怎样 -- 包括两条曲线都动时的“不确定”情形);以及对线性供求做代数求 解。C部分要求画出图并给每次移动加箭头。 AskSia Library . ECB1101 · 双语 Bilingual 3. 1 The demand curve 3. 1 需求曲线 The law of demand: holding all else equal, as a good's price rises, the quantity demanded falls. Demand therefore slopes downward. Read it two ways - at each price, how much buyers want; and for each quantity, the most a buyer will pay (their marginal value). 需求定律:其他条件不变时,某商品价格上升,其需求量下 降。因此需求曲线向下倾斜。可两种读法 -- 在每个价格上 买方想要多少;以及对每个数量,买方愿付的最高价(他们 的边际价值)。 Demand shifters (the whole curve moves) 需求移动因素(整条曲线移动) - Income - a normal good: more income shifts D right; an inferior good: more income shifts D left. ** 收入 **--* 正常品 *: 收入增加使 D右移 ;* 劣等品 *: 收入增加使 D 左移。 → Prices of related goods - substitutes & complements. ** 相关商品价格 **-- 替代品与互补品。 - Tastes / preferences. ** 口味 ** /偏好。 - Expectations of future price or income. | 对未来价格或收入的 ** 预期 **。 → Number of buyers in the market. 市场中的 ** 买方数量 **。 3. 2 The supply curve 3. 2 供给曲线 The law of supply: holding all else equal, as price rises, the quantity supplied rises - higher prices make production worthwhile. Supply slopes upward; read each point as the lowest price a seller will accept (their marginal cost). 供给定律:其他条件不变时,价格上升,供给量上升 -- 更 高的价格使生产更值得。供给曲线向上倾斜;每个点读作卖 方愿意接受的最低价(他们的边际成本)。 Supply shifters (the whole curve moves) 供给移动因素(整条曲线移动) - Input (factor) prices - cheaper inputs shift S right. ** 投入品(要素)价格 **-- 投入品变便宜使 S 右移。 Price ($) S
- 第三优先：弹性 Week 4（B 部分常考）
- 中点法 + 分类 + 总收益法则 + 税负归宿一句话。[16]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfA demand curve tells you that quantity falls when price rises. Elasticity answers the next question - by how much? It converts a slope into a single, unit-free figure you can compute, compare across goods and tie directly to revenue. This is the most calculation-heavy week of the unit, and the engine of Quiz 1. 需求曲线告诉你价格上升时数量会下降。弹性(elasticity)回答下一个问题 -- 下降多少?它把斜率转化为一个可计算、可跨商 品比较、并直接与收益挂钩的无单位数字。这是本课程计算量最大的一周,也是测验1(Quiz 1)的引擎。 ★ What the exam asks here 这里考试问什么 Compute price elasticity of demand from a two-row schedule by the midpoint method; classify it as elastic / inelastic / unit-elastic; apply the total-revenue rule to say which way to move price; and read off income and cross-price elasticities by their sign. Quiz 1 (Week 5) is built almost entirely from this chapter - MCQ + a calculation + a graph. Answers are usually clean numbers and a calculator is allowed, so show every step. 用中点法从两行表算需求价格弹性;把它归类为富有弹性/缺乏弹性/单位弹性;应用总收益法则说出价格该往哪动; 并按符号读出收入和交叉价格弹性。测验1(第5周)几乎全部由本章构成 -- MCQ+一道计算+一张图。答案通常是干 净的数字且允许用计算器,所以每一步都要写出来。 4. 1 Price elasticity of demand - the midpoint method 4. 1 需求价格弹性(PED) –––中点法 The price elasticity of demand (PED) is the percentage change in quantity demanded divided by the percentage change in price. ECB1101 computes both percentages by the midpoint (arc) method: each change is divided by the average of the two values, not the starting value. 需求价格弹性(PED)是需求量的百分比变化除以价格的百分比变化。ECB1101 用中点(弧)法(midpoint method)算这两个百分 比:每个变化都除以两值的平均,而非起始值。 MIDPOINT (ARC) ELASTICITY PED where %4Q = (Q2-Q1) + [(Q1+Q2)/2] %AP %AP = (P2-P1) + [(P1+P2) /2] Because demand slopes down, %4Q and %AP have opposite signs, so PED is negative. The course classifies on the absolute value |PED|. AskSia Library · ECB1101 · 双语 Bilingual 由于需求向下倾斜,%△Q和%△P 符号相反,所以 PED 为负。课程按绝对值 |PED|来分类。 § Why ECB1101 uses the midpoint, not the point, formula ECB1101 为何用中点法而非点弹性公式 The midpoint method divides each change by the average of the start and end values. Its one virtue is direction- independence: the elasticity from $8-$10 equals the elasticity from $10-$8, because both use the same midpoint as the base. A plain %-change formula would give two different answers depending on which price you start from. This is the method the Workshop solutions and Quiz 1 use - match it exactly. 中点法把每个变化除以起止值的平均。它唯一的优点是方向无关:$8→$10 的弹性等于 $10→$8 的弹性,因为两者都以 同一个中点为基。普通的百分比变化公式会因你从哪个价格起算而给出两个不同答案。这是习题课答案和测验1所用的 方法 -- 精确匹配它。 The three regions 三个区域 | PED | Name Meaning > 1 Elastic Q responds more than proportionally to price = 1 Unit-elastic Q changes in the same proportion as price[18]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfTOTAL - REVENUE RULE Inelastic (|PED | <1): raise P - TR rises Elastic (| PED | >1): raise P - TR Falls Unit-elastic (|PED |=1): TR is unchanged (at its max) AskSia Library · ECB1101 · 双语 Bilingual ** 市场界定 **-- 狭义市场(单一品牌)比广义市场(所有 食品)更富有弹性。 ✓ Exam move - which way to move price 考试技巧 -- 价格该往哪个方向动 To raise revenue, push price toward the inelastic region. If demand is inelastic, raise the price (little quantity lost). If elastic, cut the price (lots of quantity gained). TR peaks where |PED| = 1. 要提高收益,把价格推向缺乏弹性的区域。若需求缺乏弹性,涨价(数量损失很少)。若富有弹性,降价(数量收获很多)。 TR 在 |PED| = 1 处达峰。 一 i The drug-interdiction application (Workshop) 缉毒应用案例(习题课) Demand for an addictive drug is inelastic. Cutting supply (interdiction) raises the price more than proportionally, so total expenditure on drugs - sellers' revenue - rises. Because users need more money to buy the same drugs, drug- related crime may increase. The elasticity sign drives the whole policy conclusion. 对成瘾性毒品的需求缺乏弹性。削减供给(缉毒)使价格不成比例地上升,所以毒品上的总支出 -- 卖方的收益 -- 上升。 因为吸毒者需要更多钱来买同样的毒品,与毒品相关的犯罪可能增加。弹性的符号驱动了整个政策结论。 ! PES is a ratio, not a multiplier PES 是比率,不是倍数 "PES = 2" means a 1% price rise raises quantity supplied by 2% - not that quantity doubles. The Workshop flags this as a T/F trap. Elasticity is always a percentage-on-percentage ratio. “PES= 2”意味着价格上升1% 使供给量上升 2% -- 而非数量翻倍。习题课把这标为判断题陷阱。弹性永远是百分比 对百分比的比率。 AskSia Library . ECB1101 · 双语 Bilingual CH 4 . WORKED MIDPOINT - - CHAPTER 4 (CONT. ) WORKED . QUIZ 1 STAPLE Worked example: the midpoint calculation 例题:中点法计算 DVD demand schedule - PED, then income elasticity, step by step DVD 需求表 -- PED,再算收入弹性,一步步来 This is the canonical Quiz 1 item, transcribed from the Week-4 Workshop: a demand schedule at two income levels. Read two rows, plug them into the midpoint formula, and classify. The numbers below match the Workshop's worked answers exactly. 这是经典的测验1题目,抄自第4周习题课(Workshop):两个收入水平下的需求表。读两行,代入中点公式,分类。下面的 数字与习题课的标准答案完全一致。 Price P Q at I = $10,000 Qa at I = $12,000 $8 $10[4]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfi 4 . A corrective tax = the external effect 4 · 矫正税 = 外部效应 A negative externality means SMC > PMC: the market over-produces. The fix is a Pigouvian tax = the marginal external cost (SMC - PMC, not the price gap), which lifts private cost to social cost and restores the efficient Q. Positive externality - subsidy = external benefit. Public good = non-rival + non- excludable - free-riding. ** 负外部性(negative externality) ** 意味着 ** SMC > PMC **: 市场 ** 生产过多 **。 对策是 ** 庇古税 (Pigouvian tax)= 边际外部成本 ** (SMC - PMC,* 不是*价格差),它把私人成本抬升至社会成本,恢复 有效的Q。正外部性→补贴=外部收益。公共物品 = 非竞争性+非排他性→搭便车(free-riding)。 AskSia Library . ECB1101 · 双语 Bilingual ✓ 2 . Elasticity by the midpoint method 2 . 用中点法(midpoint method)算弹性 ECB1101's default is the midpoint (arc) method: divide each %-change by the average of the two values. If demand is inelastic (|E| < 1), raise price to raise revenue; if elastic, cut it; TR peaks at |E| = 1. On a tax, the less-elastic side bears more - it cannot walk away. ECB1101 默认用 ** 中点法(arc method) **: 每个百分 比变化除以两值的 ** 平均 **。 若需求 ** 缺乏弹性 ** ([E]<1), ** 提价 ** 可增收入;若 ** 富有弹性 ** ,则 降价;TR在 | == 1时达到峰值。对于税收, ** 弹性 较小的一方承担更多 **-- 它无处可逃。 § 3 . P = MC competition / MR = MC monopoly 3 . 完全竞争 P = MC / 垄断 MR = MC A price taker has P = MR, so produces where P = MC; shut down if P < AVC; long run, free entry drives P to min ATC and profit to zero. A monopolist sets MR = MC for the quantity, then reads price off demand (MR = a - 2bQ, twice the slope). Because P > MC it under- produces - deadweight loss. ** 价格接受者(price taker) ** P = MR,故在 ** P = MC ** 处生产 ;** P <AVC 则停业(shut down) **; 长 期下自由进入将 P 压到 ** min ATC **、 利润压到 ** 零 **。** 垄断者(monopolist) ** 令 ** MR = MC ** 定数 量,再从 ** 需求曲线 ** 读出价格 (MR = a-2bQ,斜 率两倍)。因P>MC 而生产不足→无谓损失。 ✓ 5 . The four market structures at a glance 5 · 四种市场结构一览 Perfect competition: many firms, identical good, no barriers, P = MR = MC, zero LR profit. Monopolistic competition: many, differentiated, P > MC, excess capacity, zero LR profit (P = ATC tangency). Oligopoly: few firms, interdependent, market power. Monopoly: one firm, barriers, P > MR = MC, DWL. Markup (P - MC) > 0 for the last three. ** 完全竞争 **: 企业众多、产品同质、无壁垒,P= MR = MC,长期零利润 。** 垄断竞争 **: 众多、差异 化,P> MC,过剩产能,长期零利润(P=ATC相 切) 。** 寡头(oligopoly) **: 少数企业、相互依存、有 市场势力 。** 垄断 **: 单一企业、有壁垒,P> MR = MC,有 DWL。后三者加成(P-MC)>0。 ★ 6 . ALWAYS draw and fully label every Section-C graph 6 · C 部分每张图都要画出并完整标注 Axes named, both curves drawn, equilibrium marked, shifts shown with arrows, and CS / PS / DWL shaded and labelled. ECB1101 deducts marks for unlabelled axes, curves and movements - these are the easiest marks in the paper and an arithmetic slip cannot cost them. Draw the diagram even when the question does not explicitly ask. 坐标轴要命名, ** 两条曲线 ** 都画出,标出 ** 均衡点 ** , ** 用箭头表示移位 ** ,CS / PS / DWL ** 阴影并 标注 **。 ECB1101 ** 对未标注的坐标轴、曲线和移动 扣分 **-- 这些是全卷最易得的分,算术失误也夺不 走它们。即便题目没明说,也要画图。 ~1. 3 min PER MARK - PACE IT 每分 -- 把握节奏 130 min FOR 100 MARKS 对应 100 分 40 mk SECTION C - LEAVE TIME TO DRAW C 部分 -- 留时间画图 HURDLE - JUST BANK THE MARKS 门槛 -- 把分收下即可 ! Pace it: 100 marks in 130 minutes 把握节奏:130 分钟拿 100 分
- 第四优先：概念类（A 部分）
- 机会成本/沉没成本、PPF、实证规范、公共物品/外部性关键句。[20]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdf★ How ECB1101 tests this ECB1101 如何考查这一点 Week 1 ideas surface as Section A multiple-choice and true/false concept checks: name the opportunity cost of a choice (ignoring sunk costs), read a point as efficient / inefficient / unattainable on a PPF, decide whether a statement is positive or normative, and apply the MB = MC rule. The recurring trap is confusing what you spent with what you gave up. 第1周的理念以 A 部分选择题和判断题概念检查出现:说出一个选择的机会成本(忽略沉没成本),把 PPF 上一个点读作 有效率/无效率/不可达,判断一句话是实证还是规范,并应用MB= MC 法则。反复出现的陷阱是把你花掉的与你放 弃的混为一谈。 1. 1 Scarcity & the economic problem 1. 1 稀缺与经济问题 Human wants are unlimited; the resources to satisfy them - time, labour, capital, land - are finite. That gap is scarcity, and it forces every individual, firm and society to choose. To choose one thing is, at the same instant, to choose not to do something else. Economics studies how scarce resources are allocated among competing uses, and the tool that values any choice is its opportunity cost. - 人的欲望无限;满足欲望的资源 -- 时间、劳动、资本、土地 -- 是有限的。这道缺口就是稀缺(scarcity),它迫使每个人、 每家企业和整个社会去选择。选择一件事,就在同一刻选择了不做另一件事。经济学研究稀缺资源如何在相互竞争的用途间配 置,而衡量任何选择的工具就是它的机会成本。 - 1. 2 Opportunity cost 1. 2 机会成本 AskSia Library · ECB1101 · 双语 Bilingual The opportunity cost of a choice is the value of the next-best alternative forgone - the single best thing you gave up to get what you chose. It is not the sum of everything you did not do, and it is not the dollar price on the tag. For students the biggest cost is usually time: the wage you could have earned, the study you could have done. 一个选择的机会成本(opportunity cost)是被放弃的次优选项的价值 -- 你为得到所选之物而放弃的那一件最好的东西。它不 是你没做的所有事之和,也不是标签上的金额。对学生而言最大的成本通常是时间:你本可赚到的工资、本可完成的学习。 DEFINITION opportunity cost = value of the next-best alternative forgone ! Sunk costs are not opportunity costs 沉没成本不是机会成本 A sunk cost is money already spent that cannot be recovered - a non-refundable ticket, last semester's fees. It is the same whatever you choose next, so it is irrelevant to the decision. Rational choice looks only forward: weigh the marginal benefit against the opportunity cost of the next action, and ignore what is already gone. 沉没成本(sunk cost)是已经花掉、无法收回的钱 -- 一张不可退的票、上学期的学费。无论你接下来怎么选它都一样, 所以它与决策无关。理性选择只向前看:权衡下一步行动的边际收益与机会成本,无视已经逝去的。 AskSia Library . ECB1101 · 双语 Bilingual CH 1 . PPF - CHAPTER 1 (CONT. ) The production possibility frontier 生产可能性边界 (PPF) Drawing scarcity, trade-offs and efficiency in one curve 用一条曲线画出稀缺、权衡与效率 1. 3 The PPF 1. 3 PPF The production possibility frontier (PPF) shows the maximum combinations of two goods an economy can produce when all resources are fully and efficiently used. It makes scarcity visible: to get more of one good you must move along the curve and give up some of the other - and that sacrifice is the opportunity cost. 生产可能性边界(PPF)展示了当所有资源被充分且有效利用 时,一个经济体能生产的两种商品的最大组合。它让稀缺可 见:要多生产一种商品,你必须沿着曲线移动、放弃一些另 一种 -- 而那份牺牲就是机会成本。 - On the curve - efficient (no waste; producing the most possible). 曲线 **** → ** 有效率 ** (无浪费;产出尽可能多)。[4]Source: monash-ecb1101-microeconomics-exam-bible-bilingual.pdfi 4 . A corrective tax = the external effect 4 · 矫正税 = 外部效应 A negative externality means SMC > PMC: the market over-produces. The fix is a Pigouvian tax = the marginal external cost (SMC - PMC, not the price gap), which lifts private cost to social cost and restores the efficient Q. Positive externality - subsidy = external benefit. Public good = non-rival + non- excludable - free-riding. ** 负外部性(negative externality) ** 意味着 ** SMC > PMC **: 市场 ** 生产过多 **。 对策是 ** 庇古税 (Pigouvian tax)= 边际外部成本 ** (SMC - PMC,* 不是*价格差),它把私人成本抬升至社会成本,恢复 有效的Q。正外部性→补贴=外部收益。公共物品 = 非竞争性+非排他性→搭便车(free-riding)。 AskSia Library . ECB1101 · 双语 Bilingual ✓ 2 . Elasticity by the midpoint method 2 . 用中点法(midpoint method)算弹性 ECB1101's default is the midpoint (arc) method: divide each %-change by the average of the two values. If demand is inelastic (|E| < 1), raise price to raise revenue; if elastic, cut it; TR peaks at |E| = 1. On a tax, the less-elastic side bears more - it cannot walk away. ECB1101 默认用 ** 中点法(arc method) **: 每个百分 比变化除以两值的 ** 平均 **。 若需求 ** 缺乏弹性 ** ([E]<1), ** 提价 ** 可增收入;若 ** 富有弹性 ** ,则 降价;TR在 | == 1时达到峰值。对于税收, ** 弹性 较小的一方承担更多 **-- 它无处可逃。 § 3 . P = MC competition / MR = MC monopoly 3 . 完全竞争 P = MC / 垄断 MR = MC A price taker has P = MR, so produces where P = MC; shut down if P < AVC; long run, free entry drives P to min ATC and profit to zero. A monopolist sets MR = MC for the quantity, then reads price off demand (MR = a - 2bQ, twice the slope). Because P > MC it under- produces - deadweight loss. ** 价格接受者(price taker) ** P = MR,故在 ** P = MC ** 处生产 ;** P <AVC 则停业(shut down) **; 长 期下自由进入将 P 压到 ** min ATC **、 利润压到 ** 零 **。** 垄断者(monopolist) ** 令 ** MR = MC ** 定数 量,再从 ** 需求曲线 ** 读出价格 (MR = a-2bQ,斜 率两倍)。因P>MC 而生产不足→无谓损失。 ✓ 5 . The four market structures at a glance 5 · 四种市场结构一览 Perfect competition: many firms, identical good, no barriers, P = MR = MC, zero LR profit. Monopolistic competition: many, differentiated, P > MC, excess capacity, zero LR profit (P = ATC tangency). Oligopoly: few firms, interdependent, market power. Monopoly: one firm, barriers, P > MR = MC, DWL. Markup (P - MC) > 0 for the last three. ** 完全竞争 **: 企业众多、产品同质、无壁垒,P= MR = MC,长期零利润 。** 垄断竞争 **: 众多、差异 化,P> MC,过剩产能,长期零利润(P=ATC相 切) 。** 寡头(oligopoly) **: 少数企业、相互依存、有 市场势力 。** 垄断 **: 单一企业、有壁垒,P> MR = MC,有 DWL。后三者加成(P-MC)>0。 ★ 6 . ALWAYS draw and fully label every Section-C graph 6 · C 部分每张图都要画出并完整标注 Axes named, both curves drawn, equilibrium marked, shifts shown with arrows, and CS / PS / DWL shaded and labelled. ECB1101 deducts marks for unlabelled axes, curves and movements - these are the easiest marks in the paper and an arithmetic slip cannot cost them. Draw the diagram even when the question does not explicitly ask. 坐标轴要命名, ** 两条曲线 ** 都画出,标出 ** 均衡点 ** , ** 用箭头表示移位 ** ,CS / PS / DWL ** 阴影并 标注 **。 ECB1101 ** 对未标注的坐标轴、曲线和移动 扣分 **-- 这些是全卷最易得的分,算术失误也夺不 走它们。即便题目没明说,也要画图。 ~1. 3 min PER MARK - PACE IT 每分 -- 把握节奏 130 min FOR 100 MARKS 对应 100 分 40 mk SECTION C - LEAVE TIME TO DRAW C 部分 -- 留时间画图 HURDLE - JUST BANK THE MARKS 门槛 -- 把分收下即可 ! Pace it: 100 marks in 130 minutes 把握节奏:130 分钟拿 100 分
- 第一优先：Section C 两大模型
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5）你给我三个信息，我就能把你的复习变成“可执行的冲刺清单”
- 你回我这三项，我就按你的情况把上面内容变成 逐日计划 + 每天必做题型（并优先补你最容易丢分的点）：
- 你 final 还有几天？（例如：3 天/7 天/14 天）
- 你最怕的是哪块：税/DWL、弹性、垄断、供需比较静态、机会成本？
- 你现在做 Section C 画图：最大问题是 来不及画/不会标注/算不动/不知道从哪一步开始？
- （可选）如果你愿意，我也可以把你这门课“你最薄弱的 3 个考点 + 你最容易犯的陷阱”记住；你下次只要说“复习 ECB1101”，我就直接按你的弱点顺序帮你冲刺。
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