An analyst has developed the following probability distribution for the rate of return for a common stock. scenario probability rate of return 1 0.21 −15 % 2 0.49 8 % 3 0.30 25 % a. calculate the expected rate of return. (round intermediate calculations to at least 4 decimal places. round your answer to 2 decimal places.) b. calculate the variance and the standard deviation of this probability distribution. (use the percentage values for your calculations (for example 10% not 0.10). round intermediate calculations to at least 4 decimal places. enter your answer as a percentage rounded to 2 decimal places.) variance %2 standard deviation %