An aptitude test has a mean of 400 and a standard deviation of 40. The test scores are normally distributed. If 2500 people take the test, find the number of people who will score between 314 and 490.
A) 35
B) 2430
C) 70
D) 2465

Question

Quizplus · Accepted Answer

The z-score for a score of 314 is (314 - 400) / 40 = -2.15. The z-score for a score of 490 is (490 - 400) / 40 = 2.25. The area under the normal curve between z-scores of -2.15 and 2.25 is 0.9876. Therefore, the number of people who will score between 314 and 490 is 0.9876 * 2500 = 2469.

An Aptitude Test Has a Mean of 400 and a Standard