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Question
Math
Posted 9 months ago

The grades on a math midterm at Springer are roughly symmetric with μ=72\mu=72 and σ=4.5\sigma=4.5.

Stephanie scored 86 on the exam.
Find the z-score for Stephanie's exam grade. Round to two decimal places.
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Answer from Sia
Posted 9 months ago
Solution by Steps
step 1
Calculate the difference between Stephanie's score and the mean
$z = \frac{X - \mu}{\sigma}$ where $X = 86$, $\mu = 72$, and $\sigma = 4.5$.
step 2
Substitute the given values into the z-score formula
$z = \frac{86 - 72}{4.5}$
step 3
Compute the numerator of the z-score formula
$86 - 72 = 14$
step 4
Divide the difference by the standard deviation
$z = \frac{14}{4.5}$
step 5
Calculate the z-score and round to two decimal places
$z = 3.111111111111111...$
$z \approx 3.11$ (rounded to two decimal places)
Answer
z=3.11z = 3.11
Key Concept
Z-score Calculation
Explanation
The z-score represents the number of standard deviations a data point is from the mean. It is calculated by subtracting the mean from the data point and then dividing by the standard deviation.

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