Youve observed the following returns on Crash-n-Burn Computers stock over the past five years: 8 percent, 15 percent, 19 percent, 31 percent, and 21 percent.

a. What was the arithmetic average return on the company's stock over this five-year period?

b-1. What was the variance of the company's returns over this period?

b-2. What was the standard deviation of the company's returns over this period?