Samples of n = 200 items were selected hourly over a 100-hour period, and the sample proportion

Question:

Samples of n = 200 items were selected hourly over a 100-hour period, and the sample proportion of defectives was calculated each hour. The mean of the 100 sample proportions was .041.
a. Use the data to find the upper and lower control limits for a p chart.
b. Construct a p chart for the process and explain how it can be used.