The scores on a mathematics exam have a mean of 70 and a standard deviation of 5. Find the x-value that corresponds to the z-score 2.33.
A)81.7
B)58.4
C)75.0
D)72.3

Question

Quizplus · Accepted Answer

We use the formula:
z = (x - mean) / standard deviation
2.33 = (x - 70) / 5
11.65 = x - 70
x = 81.65
Rounding to one decimal place gives x = 81.7. So the answer is choice A). We can use the formula:
z = (x - μ) / σ
where z = 2.33, μ = 70, σ = 5
Solving for x, we get:
x = zσ + μ
x = 2.33(5) + 70
x = 81.65
Rounding to one decimal place, we get:
x = 81.7
Therefore, the answer is A).

The Scores on a Mathematics Exam Have a Mean of 70