Question

A score that is 12 points below the mean corresponds to a z-score of z= -1.50. what is the standard deviation?

Answer 1

Answer:  8

Work Shown

z = (x - mu)/sigma

-1.50 = (-12)/sigma

-1.50sigma = -12

sigma = -12/(-1.50)

sigma = 8

Note the phrasing "12 points below the mean" indicates the distance from x to mu is 12 units. We'll have x-mu = -12 to indicate below the mean. If x-mu = 12 then we'd be 12 units above the mean.