Is there a difference in the yields of different types of investments? The file SavingsRate-MMCD contains the

Question:

Is there a difference in the yields of different types of investments? The file SavingsRate-MMCD contains the yields for a money market account and a five-year certificate of deposit (CD) for 25 banks in the United States, as of March 29, 2010.
a. Construct a 95% confidence interval estimate for the mean yield of money market accounts.
b. Construct a 95% confidence interval estimate for the mean yield of five-year certificates of deposits.
c. Compare the results of (a) and (b).