You've observed the following returns on Mary Ann Data Corporation's stock over the past five years: 27

Question:

You've observed the following returns on Mary Ann Data Corporation's stock over the past five years: 27 percent, 13 percent, 18 percent, −14 percent, and 9 percent.
What was the arithmetic average return on Mary Ann's stock over this five-year period?
What was the variance of Mary Ann's returns over the period above in question 4? The standard deviation?