Telephone inquiries of 100 cell phone company customers are monitored daily at random. Incidents of incorrect information or other nonconformities (such as rudeness to customers) are recorded. The data for last two weeks is as follows:
|
Day
|
Number of "nonconformities"
|
|
1
|
5
|
|
2
|
10
|
|
3
|
27
|
|
4
|
17
|
|
5
|
12
|
|
6
|
7
|
|
7
|
12
|
|
8
|
25
|
|
9
|
15
|
|
10
|
10
|
a. What is the appropriate control chart(s) to construct with this data?
b. What are the ± 3 sigma upper and lower control limits?
c. What does the control chart tell you about the phone company's operators?