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%?

49.9%
1%
50%
47.7%

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%?

 49.9%
 1%
 50%
 47.7%

debbieg · Answer

What are the z-scores for this range of scores? E.g., for X=72, z=? and for X=87, z=?