If the economy booms, Meyer&Co. stock will have a return of 21.5 percent. If the economy goes into a recession, the stock will have a loss of 13.8 percent. The probability of a boom is 64 percent while the probability of a recession is 36 percent. What is the standard deviation of the returns on the stock?

State of Economy Probability of State of Economy Return if State Occurs Stock x Stock y Stock z 10.80% 4.20% 13.20% 18.10% 26.10% 17.60% Normal .77 Boom .23