In one history class, 34 students took an exam. The mean of the exam was 52 with
a standard deviation of 13. If the instructor is going to assume data are
normally distributed and assign grades on a curve, then she will assign an A to
the top 10% of the class, B's to the next 15%, and C's students in the next 60%
of the students. What is the minimum score for A? What is the grade range for a
B? What is the grade range for a C?