Carson Inc.'s manager believes that economic conditions during the next year will be strong, normal, or weak, and she thinks th the firm's returns will have the probability distribution shown below. What's the standard deviation of the estimated returns? (Hint: Use the formula for the standard deviation of a population, not a sample.) Do not round your intermediate calculations. Economic Prob. Return Strong 30% 40.096 Normal 4096 10.0% 30% O2288% Conditions Weak -16.0% b, 12.53% @_. 28.0296 O d. 21.71% O e 15.35%