How different are the rates of return of money market

How different are the rates of return of money market accounts and certificates of deposit that vary in length of their term? The data in MMCD Rate contain these rates for banks in a suburban area. (Data extracted from "Consumer Money Rates," Newsday, June 24, 2010, p. A43.)
a. At the 0.05 level of significance, determine whether there is evidence of a difference in the mean rates for these investments.
b. What assumptions are necessary to perform this test?
c. If appropriate, use the Tukey procedure to determine which investments differ.
d. Do you think that there was a significant block effect in this experiment? Explain.