A statistics student receives a grade of 90 on a statistics midterm. If the corresponding z-score equals +1.5 and the standard deviation equals 7, determine the average grade on this exam.
A) 74.0
B) 79.5
C) 74.7
D) 79.3
E) 75.0

Question

Quizplus · Accepted Answer

We can use the formula:

z-score = (x - μ) / σ

Where:
x = the grade received (90 in this case)
μ = the average grade
σ = the standard deviation (7 in this case)
z-score = 1.5

Substituting these values and solving for μ:

1.5 = (90 - μ) / 7
10.5 = 90 - μ
μ = 79.5

Therefore, the average grade on this exam is 79.5. So, the best choice is B.

A Statistics Student Receives a Grade of 90 on a Statistics