The following is the frequency distribution for the speeds of a sample of automobiles traveling on an interstate highway.
Speed
Miles per Hour Frequency
50 - 54 2
55 - 59 4
60 - 64 5
65 - 69 10
70 - 74 9
75 - 79 5
Refer to Exhibit 3-4. The mean is
(A) 35
(B) 670
(C) 10
(D) 67
(E) None of the above answers is correct.