The annual percentage returns on common stocks over a 7-year period were as follows:
4.0% 14.3% 19.0% -14.7% -26.5% 37.2% 23.8%
Over the same period the annual percentage returns on U.S.
Treasury Bills were as follows:
6.5% 4.4% 3.8% 6.9% 5.8% 5.1% 8.0%
a. Compare the means of these two population distributions
b. Compare the standard deviations of these two population distributions.