The following is an incomplete simple frequency distribution table for student grades on a college professor's statistics exam.
Grades (%) ___________________ Frequency
87-95 ........................................4
A-B .........................................17
69-77 ........................................5
60-C .........................................7
51-59 ........................................D
N = 40
(a) Find the missing values for A, B, C, and D.
(b) If students scoring less than 69% on this exam receive a failing grade, was this a difficult test? Explain.