An airline operates a call center to handle customer questions and complaints. The airline monitors a sample of calls to help ensure that the service being provided is of high quality. Ten random samples of calls each were monitored under normal conditions. The center can be thought of as being in control when these samples were taken. The number of calls in each sample of not resulting in a satisfactory resolution for the customer is as follows: 4 5 3 2 3 3 4 6 4 7

Required:
a. What is an estimate of the proportion of calls not resulting in a satisfactory outcome for the customer when the center is in control?
b. Construct the upper and lower limits for a p chart for the manufacturing process, assuming each sample has 100 calls.