The grades for the Statistics final exam of a large class are normally distributed with a mean of 42 and a standard deviation of 16. The examiner is to assign Grades according to the following rule:
Grade A: top 10%
Grade B: the next 20%
Grade C: the middle 40%
Grade D: the next 20%
Grade F: the bottom 10%
Find the lowest score on the final exam that would qualify a student for:
(a) a Grade A
(b) a Grade C