the stock x is expected to earn 0.32 in boom, 0.16 in normal economy and -0.18 in bust. stock y is expected to earn 0.17 in boom, 0.12 in normal economy and -0.08 in bust. the probability of a boom is 5 oercent, the probability of a normal economy is 91 percent and the probability of bust is 4 percent. what is the standard deviation of returns on a portfolio that is invested in stock x and y if the 30 percent of the portfolio is invested in stock x and 70 percent is invested in stock y??