Using four samples of200 credit card statements each, an auditor found the following number of erroneous statements in each sample:

a. Determine the proportion of defectives in each sample.
b. If the true proportion of defectives for this process is unknown, what is your best estimate of it?
c. What is your estimate of the mean and standard deviation of the sampling distribution of the sample proportion of defectives for samples of 200?
d. What control limits would give an alpha risk of .03 for this process?
e. What alpha risk would control limits of .047 and .003 provide?
f. Using control limits of .047 and .003, is the process in control?
g. Suppose that the long-term proportion of defectives of the process is known to be 2 percent. What are tire values of the mean and standard deviation of die sampling distribution?
h. Construct a p-contro1 chart for the process, assuming a proportion of defectives of 2 percent, and Two Sigma control limits. Is tire process in control?

Sample Number of err 4 2 5 9