Please help Im trying to calculate the standard deviation of a portfolio of 3 assets security B C and D with the information in this table

3. Calculate the standard deviation of portfolio of 3 Assets (Security B, C, and D)? Prob. Security A Security C Security D Security E Recession 0.1 3.0% -29.5% 24.5% 3.5% -19.5% Below avg 0.2 3.0% -95% 10.5% -16.5% -5.5% Average 0.4 3.0% 12.5% 0.5% 7.5% Above avg 0.2 3.0% 275% -5.0% 38.5% 22.5% Boom 0.13.0% 42.5% -20.0% 23.5% 35.5%