An inspector counted the number of defective monthly billing statements of a company telephone in each of 20 samples. Using the following information, construct a control char that will describe 99.74 percent of the chance variation in the process when the process is in control. Each sample contained 100 statements.

Sample	Number of Defectives	Sample	Number of Defectives	Samples	Number of Defectives	Samples	Number of Defectives
1	4	6	11	11	8	16	10
2	10	7	10	12	12	17	8
3	12	8	22	13	9	18	12
4	3	9	13	14	10	19	10
5	9	10	10	15	21	20	16

Total Defectives: 220