15. A doctor’s office staff studied the waiting times for patients who arrive at the office with a request for emergency service. The following data with waiting times in minutes were collected over a one-month period.

2 5 10 12 4 4 5 17 11 8 9 8 12 21 6 8 7 13 18 3 Use classes of 0–4, 5–9, and so on in the following:

a. Show the frequency distribution.

b. Show the relative frequency distribution.

c. Show the cumulative frequency distribution.

d. Show the cumulative relative frequency distribution.

e. What proportion of patients needing emergency service wait 9 minutes or less?