From past history, the scores on a statistics test are normally distributed with a mean of 70% and a standard deviation of 5%. To earn a "B" on the test, a student must be in the top 15% of the class. What should a student score to receive a "B"?
A) 77.21
B) 75.49
C) 81.48
D) 76.90
E) None of the choices are correct

Question

Quizplus · Accepted Answer

The top 15% of the class corresponds to a z-score of 1.04. Using the formula z = (x - mu) / sigma, we can solve for x:1.04 = (x - 70) / 5x = 77.21

From Past History, the Scores on a Statistics Test Are