Question

a set of final examination grades in an introductory statistics course is normally distributed with a mean of 77 and a standard deviation of 8.the probability is 15% that a student taking the test scores higher than what grade. the probability is 15% that a student taking the test scores higher than ?

Answer 1

Let X be the final examination grade. X ~ N(77,8²) .

Let the probability of a score higher than grade a is 15/100 = 0.15

Or, P(X>a) = 0.15

So, the required grade is 89.