A student of one of the authors earned grades of 63, 91, 88, 84, and 79 on her five regular statistics tests. She earned a grade of 86 on the final exam and 90 on her
class projects. Her combined homework grade was 70. The five regular tests count for 60%
of the final grade, the final exam counts for 10%, the project counts for 15%, and homework
counts for 15%. What is her weighted mean grade? What letter grade did she earn (A, B, C, D,
or F)? Assume that a mean of 90 or above is an A, a mean of 80 to 89 is a B, and so on.