Digital Switches, Inc., produces a product called the C3PO with an advertised 0.5% failure rate. A test of products shipped from the factory to the company's testing lab found a sample average failure rate of 0.45% with a sample standard deviation of 0.15% when a sample of n = 64 observations was studied.
A. Calculate the range within which the population average failure rate can be found with 95% confidence.
B. Assuming that s = 0.15% cannot be reduced, and a sample size of n = 64, what is the minimum range within which the sample average failure rate must be found to justify with 95% confidence the advertised failure rate of 0.5%?