15. Following are the speeds of 40 cars clocked by radar on a particular road in a 35-mph zone on a particular afternoon:

30, 36, 42, 36, 30, 52, 36, 34, 36, 33, 30, 32, 35, 32, 37, 34, 36, 31, 35, 20, 24, 46, 23, 31, 32, 45, 34, 37, 28, 40, 34, 38, 40, 52, 31, 33, 15, 27, 36, 40 Make

(a) a grouped frequency table and

(b) a histogram based on the grouped frequency table. Then

(c) describe the general shape of the distribution.