In a large section of a statistics class, the points for the final exam are normally distributed, with a mean of 72 and a standard deviation of 9. Grades are to be assigned according to the following rule:

The top 10% receive A's.
The next 20% receive B's.
The middle 40% receive C's.
The next 20% received D's.
The bottom 10% receive F's.

What is the least amount of points that a student must score, on the final exam, in order to earn a C? (Round your answer to two decimal places.)

the answer is 72?

1 answer

http://davidmlane.com/hyperstat/z_table.html

area = .4
mean = 72
SD = 9
.4 are between 71.5 and 72.5
so 71.5