You decide to invest in a portfolio consisting of 15 percent Stock X, 51 percent Stock Y, and the remainder in Stock Z. Based on the following information, what is the standard deviation of your portfolio? State of Economy Probability of State Return if State Occurs of Economy Stock X Stock Y Stock Z Normal .78 10.90% 4.30% 13.30% Boom .22 18.20% 26.20% 17.70%