Need all parts! :)

The last four years of returns for a stock are as follows: 4 Year Return 1 -4.0% 2 28.0% 3 12.0% 4.0% a. What is the average annual return? b. What is the variance of the stock's returns? c. What is the standard deviation of the stock's returns? a. What is the average annual return? The average return is %. (Round to two decimal places.)