Please show work/steps for standard deviation of stock a & b so i can better understand. Thanks!

(Expected rate of return and risk) Syntex, Inc. is considering an investment in one of two common stocks. Given the information that follow investment is better, based on the risk (as measured by the standard deviation) and return? Common Stock A Probability Return 0.25 10% 0.50 17% 0.25 21% Common Stock B Probability Return 0.25 -7% 0.25 7% 0.25 16% 0.25 23% a. Given the information in the table, the expected rate of return for stock A is 16.25 %. (Round to two decimal places.) The standard deviation of stock A is 3.96%. (Round to two decimal places.) b. The expected rate of return for stock B is 9.75 %. (Round to two decimal places.) The standard deviation for stock B is 11.21 %. (Round to two decimal places.) C. Based on the risk (as measured by the standard deviation) and return of each stock, which investment is better? (Select the best choice CA Stock A is better because it has a higher expected rate of return with less risk. O B. Stock B is better because it has a lower expected rate of return with more risk. Question is complete. Tap on the red indicators to see incorrect answers