Question

The points obtained by students of a class in a test are normally distributed with a mean of 60 points and a standard

deviation of 5 points.

About what percent of students have scored less than 45 points?

0.15
2.5
15.5
34

Answer 1

0.135%

Explanation:

Given :

Mean, m = 60

Standard deviation, σ = 5

x = 45

The Zscore = (x - m) / σ

Z = (45 - 60) / 5 = - 15 / 5 = - 3

P(Z < - 3) = 0.0013499

0.0013499 * 100%

= 0.13499%

Only about 0.135% scored below 45