The number of customers who are not satisfied with the service provided in a retail store is found for 20 samples of size 100 and is shown in goven Table.
Construct a control chart for the proportion of dissatisfied customers. Revise the control limits, assuming special causes for points outside the control limits.
|
Sample
|
Number of dissatisfied customers
|
Sample
|
Number of dissatisfied customers
|
|
1
|
2
|
11
|
5
|
|
2
|
5
|
12
|
4
|
|
3
|
4
|
13
|
2
|
|
4
|
3
|
14
|
5
|
|
5
|
4
|
15
|
3
|
|
6
|
2
|
16
|
12
|
|
7
|
3
|
17
|
3
|
|
8
|
2
|
18
|
2
|
|
9
|
4
|
19
|
5
|
|
10
|
11
|
20
|
2
|