please answer all parts i cant figure out the last two

You've observed the following returns on Pine Computer's stock over the past five years: 28.5 percent, 16 percent, 35 percent, 3.5 percent, and 22.5 percent. a. What was the arithmetic average return on the stock over this five-year period? Note: Do not round intermediate calculations and enter your answer as a percent rounded to 2 decimal places, e.g., 32.16. b. What was the variance of the returns over this period? Note: Do not round intermediate calculations and round your answer to 6 decimal places, e.g., .161616. c. What was the standard deviation of the returns over this period? Note: Do not round intermediate calculations and enter your answer as a percent rounded to 2 decimal places, e.g., 32.16. Answer is complete but not entirely correct