Purchasing Group is trying to determine the proportion of expense reports that contain questionable charges. It takes a random sample of 300 records and finds that 19 of the reports have one or more questionable charges.
a) Develop a 95% confidence interval on the population proportion based on the sample results.
b) Determine how large a sample they would need to take in order to be 99% certain that the maximum error in the predicted population proportion was 2%.