Chapter 2, Problem 11P

The owner of an automobile repair shop studied the waiting times for customers who arrive at the shop for an oil change. The following data with waiting times in minutes were collected over a 1-month period.

2 5 10 12 4 4 5 17 11 8 9 8 12 21 6 8 7 13 18 3

Using classes of 0–4, 5–9, and so on, show:

1. a. The frequency distribution.
2. b. The relative frequency distribution.
3. c. The cumulative frequency distribution.
4. d. The cumulative relative frequency distribution.
5. e. The proportion of customers needing an oil change who wait 9 minutes or less.