Carson Inc.'s manager believes that economic conditions during the next year will be strong, normal, or weak, and she thinks that the firm's returns will have the probability distribution shown below. What's the standard deviation of the estimated returns? (pay attention to the negative return in weak economic scenario) Economic Conditions Strong Normal Weak 15.88% 21.89% 19.37% O22 28% 20.92% Prob 30% 40% 30% Return 34.0% 10.0% -16.0%