A marketing analyst is studying the variability in customer purchase amounts between shopping mall stores and "big box" discount stores. She suspects the variability is different between those stores due to the nature of the customers involved. To investigate this issue in detail, she compiled two random samples each consisting of 26 purchase amounts at shopping mall stores and discount stores.

a. State the appropriate hypotheses to test whether the variance of the purchase amounts differs between the two types of stores.

b. Construct the 95% confidence interval for the ratio of the population variances. Assume the purchase amount distributions are normally distributed.

c. Use the computed confidence interval to test whether the variance of the purchase amounts differs between the two stores at the 5% significance level.

d. Confirm your conclusion using Excel's F.TEST function to calculate the p-value.