. After number of complaints about its directory assistance, a telephone company examined samples of calls to determine the frequency of wrong numbers given to callers. Each sample consisted of 100 calls. The manager stated that the error rate is about 4 percent. Construct a 3 sigma control limits and using = 0.03. is the process in control? Is the manager assertion about the error rate correct? Explain.

Observation 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

No. of Errors 6 4 5 8 3 6 8 4 6 7 5 6 5 4 9