Question

A set of final examination grades in an introductory statistics course is normally distributed, with a mean of 72 and a standard deviation of 9.

a) What is the probability that a student scored below 89 on this exam? (Round to 4 decimal places as needed.)

b) What is the probability that a student scored between 63 and 95? (Round to 4 decimal places ad needed.)

c) The probability is 5% that a student taking the test scores higher than what grade? (Round to the nearest integer as needed.)

d) If the professor grades on a curve (for example, the professor could give As to the top 10% of the class regardless of the score), is a student better off with a score of 81 on this exam or a grade of 71 on a different exam, where the mean is 63 and the standard deviation is 4? Explain by giving the Z value of both scores.

Answer 1