Question

A set of physics exam scores are normally distributed with a mean of 80 points and a standard deviation of 6

points. Irina got a score of 95 points on the exam.
What proportion of exam scores are lower than Irina's score?
You may round your answer to four decimal places.

Answer 1

Answer: 0.9938

Explanation:

Answer 2

The proportion of exam scores that are lower than Irina's score is 0.9938

Explanation:

Data

• mean: 80 points

• standard deviation (sd): 6 points
• value of interest (x): 95 points

z-score is computed as follows:

z = (x - mean)/sd

z = (95 - 80)/6 = 2.5

We want to find:

P(z < 2.5)

From the table attached:

P(z < 2.5) = 0.9938