Using the table below, calculate the portfolio standard deviation for a portfolio with 25% in security C and 75% in security D. Time A, % B, % C, % D, % Mkt, % 12.28 1 18.56 18.23 12.82 12.43 2 15.27 18.24 -5.82 13.45 5.99 3 14.12 14.71 12.58 4.32 12.41 4 -1.57 -6.56 -7.43 -8.54 -4.48 5 13.16 9.12 12.45 12.21 13.41 6 21.22 6.34 17.54 8.12 14.32 7.15% 8.31% 12.21% 11.57%