A medical center routinely conducts patient satisfaction surveys upon discharge and follows up with another survey within three months. The discharge and follow - up surveys, conducted on samples of five hundred discharges per month and identifying the number of patients dissatisfied with their care, are shown in Table EX 12.4.

a. Determine the fraction of dissatisfied patients at discharge and on follow - up, for each month.

b. Estimate the mean and standard deviation of the sampling distribution of dissatisfied patients at discharge and at follow - up.

c. For both surveys, determine the control limits for 95 percent confidence limits.

d. For both surveys, construct appropriate control charts and identify any observations that are not within the control limits.