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 one-month period.
2 5 11 12
5 6 4 21
22 7 9 8
6 15 6 9
5 21 16 10
(a) Develop a frequency distribution using classes of 0-4, 5-9, 10-14, 15-19, and 20-24.
Class Frequency
0-4
5-9
10-14
15-19
20-24
Total
(b) Develop a relative frequency distribution using the classes in part (a). If required, round your answers to two decimal places.
Class Relative Frequency
0-4
5-9
10-14
15-19
20-24
Total
(c) Develop a cumulative frequency distribution using the classes in part (a).
Class Cumulative Frequency
0-4
5-9
10-14
15-19
20-24
(d) Develop a cumulative relative frequency distribution using the classes in part (a). If required, round your answers to two decimal places.
Class Cumulative Relative Frequency
0-4
5-9
10-14
15-19
20-24
(e) What proportion of customers needing an oil change who wait 9 minutes or less?