ECON10003 Chap.6 Trade, Exchange Rates and External Balance

Chapter 6 of 6 · ECON10003

Trade, Exchange Rates and External Balance

Absolute productivity compares output levels; comparative advantage compares opportunity costs. Gains from specialisation arise when relative costs differ and the terms of trade fall between them. Construct each opportunity cost in consistent units and test the proposed exchange ratio against both domestic trade-offs. Do not compare one country's hours with another country's tonnes without conversion.

If Country A can make 12 wheat or 6 cloth, one cloth costs 2 wheat. If Country B can make 8 wheat or 8 cloth, one cloth costs 1 wheat; B has comparative advantage in cloth and A in wheat. Specialisation has adjustment and distributional effects even when total attainable consumption rises. The model establishes possibility, not automatic compensation or equal benefit.

With the nominal exchange rate defined as domestic currency per unit of foreign currency, the real exchange rate equals that nominal rate times the domestic price level divided by the foreign price level under the course convention. Write the quotation before calculating and preserve it when interpreting appreciation. A growth-rate decomposition helps separate currency and price contributions.

If the nominal rate is 1.50, the domestic price index 120 and the foreign price index 150, the real exchange rate is 1.20. If the nominal rate grows 3 percent, domestic prices 4 percent and foreign prices 2 percent, real depreciation is about 5 percent. Exchange-rate conventions differ across texts. A correct calculation with an unstated inverse quotation can yield a reversed verbal conclusion, so define units first.

In this chapter

What this chapter covers

01
Comparative advantage follows opportunity cost
02
The real exchange rate compares purchasing power

Worked example · free

Worked application: Comparative advantage follows opportunity cost

Q [6 marks]. The weighting used here is not an official university mark allocation; it only separates the operations in this worked answer. Apply comparative advantage follows opportunity cost to the situation described here: If Country A can make 12 wheat or 6 cloth, one cloth costs 2 wheat. If Country B can make 8 wheat or 8 cloth, one cloth costs 1 wheat; B has comparative advantage in cloth and A in wheat. Produce a reasoned conclusion that remains within the evidence boundary.

1Define variables, units, timing and the governing relation.
1Substitute the supplied values while preserving signs and denominators.
1Reconcile the result with the identity or equilibrium condition.
3Interpret the magnitude and name one model boundary.

Absolute productivity compares output levels; comparative advantage compares opportunity costs. Gains from specialisation arise when relative costs differ and the terms of trade fall between them. Construct each opportunity cost in consistent units and test the proposed exchange ratio against both domestic trade-offs. Do not compare one country's hours with another country's tonnes without conversion. Specialisation has adjustment and distributional effects even when total attainable consumption rises. The model establishes possibility, not automatic compensation or equal benefit.

Sia tip — Write units beside the inputs to comparative advantage follows opportunity cost, preserve the denominator through each operation, and substitute the result back into the originating relation.

Glossary

Key terms

Comparative advantage follows opportunity cost: Allocate production by what each economy gives up. Absolute productivity compares output levels; comparative advantage compares opportunity costs. Gains from specialisation arise when relative costs differ and the terms of trade fall between them.
The real exchange rate compares purchasing power: Combine the nominal rate with domestic and foreign prices. With the nominal exchange rate defined as domestic currency per unit of foreign currency, the real exchange rate equals that nominal rate times the domestic price level divided by the foreign price level under the course convention.

FAQ

Trade, Exchange Rates and External Balance FAQ

Which assumption gives comparative advantage follows opportunity cost its analytical force?

Absolute productivity compares output levels; comparative advantage compares opportunity costs. Gains from specialisation arise when relative costs differ and the terms of trade fall between them. Construct each opportunity cost in consistent units and test the proposed exchange ratio against both domestic trade-offs. Do not compare one country's hours with another country's tonnes without conversion.

Specialisation has adjustment and distributional effects even when total attainable consumption rises. The model establishes possibility, not automatic compensation or equal benefit. Finish by reconciling the result with the declared relation and unit.

What would a credible counterexample to the real exchange rate compares purchasing power look like?

If the nominal rate is 1.50, the domestic price index 120 and the foreign price index 150, the real exchange rate is 1.20. If the nominal rate grows 3 percent, domestic prices 4 percent and foreign prices 2 percent, real depreciation is about 5 percent. Exchange-rate conventions differ across texts. A correct calculation with an unstated inverse quotation can yield a reversed verbal conclusion, so define units first.

Put the changed input through every line before comparing the new equilibrium.

How should uncertainty be reported when using comparative advantage follows opportunity cost?

Allocate production by what each economy gives up Construct each opportunity cost in consistent units and test the proposed exchange ratio against both domestic trade-offs. Do not compare one country's hours with another country's tonnes without conversion. An independent identity, boundary value or dimensional check should expose an inconsistent answer.

Whose decision or experience becomes visible through the real exchange rate compares purchasing power?

With the nominal exchange rate defined as domestic currency per unit of foreign currency, the real exchange rate equals that nominal rate times the domestic price level divided by the foreign price level under the course convention.

If the nominal rate is 1.50, the domestic price index 120 and the foreign price index 150, the real exchange rate is 1.20. If the nominal rate grows 3 percent, domestic prices 4 percent and foreign prices 2 percent, real depreciation is about 5 percent. Move the equation across examples only after redefining variables, timing and quotation convention.

When is comparative advantage follows opportunity cost a description rather than an explanation?

Construct each opportunity cost in consistent units and test the proposed exchange ratio against both domestic trade-offs. Do not compare one country's hours with another country's tonnes without conversion. Specialisation has adjustment and distributional effects even when total attainable consumption rises. The model establishes possibility, not automatic compensation or equal benefit.

Report the omitted market, adjustment path or behavioural channel after the numerical interpretation.

Study strategy

Exam move

Set up a calculation ledger for Trade, Exchange Rates and External Balance, with separate columns for definition, algebra, substitution, reconciliation and interpretation. Index the entries by comparative advantage follows opportunity cost, the real exchange rate compares purchasing power, and write units beside every supplied value. Rework each relation after changing one input, preserving signs and denominators line by line.

Put the answer back into the identity or equilibrium condition; a result that does not reconcile is not ready for economic interpretation. Attempt the chapter questions with the formula sheet closed, then compare operations rather than final digits. Mark where an accounting statement ends and a behavioural assumption begins. Finish by stating the magnitude, unit, direction and horizon in words.

Add one channel the model omits so mathematical consistency is not mistaken for a complete forecast.

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