Question

Let's say a student scored 33 on a math achievement test for which scores are normally distributed with mean

43 and standard deviation 10.
What proportion of students finished worse than her?

Answer 1

15.87%

Explanation:

We are given;

x¯ = 33

μ = 43

σ = 10

Let's first find the z-score from the formula;

z = (x¯ - μ)/σ

Thus;

z = (33 - 43)/10

z = -10/10

z = -1

From the table attached the p-value at z = -1 is p = 0.15866 ≈ 0.1587 = 15.87%

Thus, proportion of students finished worse than her is 15.87%