Hello, thank you for taking the time to aid me in understanding this problem. I am having difficulty finding the standard deviation. I have also attached an image of the formula I used in order to get the answer I have. I appreciate the help.

Problem 11-11 Portfolio Returns and Volatilities (LO2, CFA5) Given the following information, calculate the expected return and standard deviation for a portfolio that has 31 percent invested in Stock A, 34 percent in Stock B, and the balance in Stock C. (Do not round intermediate calculations. Enter your answers as a percent rounded to 2 decimal places.) Returns State of Economy Probability of State of Economy Stock B Stock C Stock A 18% .30 19% 24% -10 .70 10 Answer is complete but not entirely correct. 5.85 % 4.95% Boom Bust Expected return Standard deviation [C.31x(-124-.0585)) (35 (002-.0585) ) 2 +(3yx (051-.0585)) +