1. An ad agency tracks the complaints, by week received, about the billboards in its city:

Week	No. of Complaints
1	4
2	5
3	4
4	11
5	3
6	9
7	4
8	5
9	4
10	11
11	3
12	9

• What type of control chart would you use to monitor this process and why?
• What are the three-sigma control limits for this process? Assume that the historical complaint rate is unknown.
• Is the process mean in control, according to the control limits? Why or why not?
• Assume now that the historical complaint rate has been four calls a week. What would the three-sigma control limits for this process be now? Is the process in control according to the control limits?