Please solve this problem like the example below

Donald received the following annual returns from his investment: Year 1 9.1% Year 2 -2.6% Year 3 15.2% Year 4 11.9% Calculate the Standard deviation of returns. Round the answer to two decimals places. Your Answer: Donald received the following annual returns from her investment: Year 1 9.6% Year 2 -4.0% Year 3 12.8% Year 4 11.8% Calculate the Standard deviation of returns. Round the answer to two decimals places. Your Answer: Step 1: Calculate arithmetic average: (9.6%-4.0%+12.8%+11.8%) / 4 = 7.55% Step 2 Calculate variance: [(9.6% -7.55%)^2+(-4.0%-7.55%)^2+(12.8%-7.55%)^2+(11.8%-7.55%)^2]/3 = 61.08 Step 3: Calculate standard deviation of returns: 61.08^(1/2) = 7.82%