Question

The grades on the last math exam had a mean of 72%. Assume the population of grades on math exams is known to be distributed normally, with a standard deviation of 5%. Approximately what percent of students earn a score between 72% and 87%?
a. 49.9%
b. 1%
c. 50%
d. 47.7%
I think it's D.

Answer 1

If the standard deviation is 5%, then the question asks what percentage of students lie between the mean (72) and 3 standard deviations (3 x 5% = 15%) above the mean. Check your normal distribution graph to figure it out.

Answer 2

I dont have a graph tho