The next year's return for FinTech Ltd depends on the state of next year's economy. The return is predicted to be 20% in a boom, 10% in average conditions, and -10% (i.e. minus 10%) in a contraction. The probability of these outcomes is 40% chance of a boom, 50% chance of average conditions, and 10% chance of a contraction. Calculate the standard deviation of expected returns for FinTech Ltd based on this data. Round your final answer to three decimal places e.g. 12.13% should be shown as 0.121. Hint: Calculate expected return first, without rounding (i.e. keep your decimal on full).

Select one:

a. 8.4%

b. 7.4%

c. 10.1%

d. 9.0%

e. 8.7%