A set of scores has a mean of 75. Jiang's score of 60 converted to a z-score of -1.5. What was the standard deviation of the distribution?
A) 5
B) 10
C) 15
D) 20

Question

Quizplus · Accepted Answer

We can use the formula for converting a score to a z-score:

z = (X - µ) / σ

where z is the z-score, X is the score, µ is the mean, and σ is the standard deviation.

We know that Jiang's score of 60 has a z-score of -1.5:

-1.5 = (60 - 75) / σ

Solving for σ, we get:

σ = (60 - 75) / -1.5 = 10

Therefore, the standard deviation of the distribution is 10, which is answer choice B.

A Set of Scores Has a Mean of 75