Frank scored 30 on a test of assertiveness.Assuming that assertiveness is normally distributed with a mean of 20 and a standard deviation of 5,what percentage of people are less assertive than Frank?
A) 50 percent
B) 68.5 percent
C) 95.5 percent
D) 97.5 percent

Question

Quizplus · Accepted Answer

To find out what percentage of people are less assertive than Frank, we need to find the area to the left of the score of 30 on the normal distribution curve.

Using a standard normal distribution table (or calculator), we can find that the z-score for a score of 30, given a mean of 20 and a standard deviation of 5, is 2.

Looking at the standard normal distribution table, we find that the area to the left of a z-score of 2 is approximately 0.9772, or 97.72%. Therefore, we can say that approximately 97.5% of people are less assertive than Frank.

Frank Scored 30 on a Test of Assertiveness