Question: A stock produced returns of 14 percent, 17percent, and -1 percent over three of the past four years, respectively. The arithmetic average for the past four years is 6 percent. What is the standard deviation of the stock's returns for the four-year period?

8. Windsor stock has produced returns of 13.8 percent, 11.7 percent, 2.3 percent, -21.4 percent, and 8.9 percent over the past five years, respectively. What is the variance of these returns?