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 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% receive D’s.

• The bottom 10% receive F’s.

Find the lowest score on the final exam that would qualify a student for an A, a B, a C, and a D.

Final Exam Grades

40% 20%/ -20% 10% 1 0% DCB A Points scored on final exam