Answer is provided, please go through step by step and show me how we get there and what calculations are being done. thank you

You observe the following three samples of returns for a particular stock: 12.60%, 7.20% and 13.30%. What is the standard deviation of returns (for this case, please use a sample size of 3 in the denominator of all calculations in which sample size is used): A. 11.03% B. 7.43%; C. 2.73%; D. 7.20%. 1 Observations In decimal 12.60% 0.1260 7.20% 0.0720 13.30% 0.1330 Total 0.3310 Average 0.11 Average 0.11 0.11 0.11 2 3 Diff from Avg Diff sad 0.02 0.00024544 (0.04) 0.00146944 0.02 0.00051378 Total 0.00222867 Variance 0.00074289 Stdev 0.02725599 In % form 2.73%