The next year's return for Apple Ltd depends on the state of next year's economy. The return is predicted to be 16% in a boom, 7% in average conditions, and -5% (i.e. minus 5%) in a contraction. The probability of these outcomes is 20% chance of a boom, 50% chance of average conditions, and 30% chance of a contraction. Calculate the standard deviation of expected returns for Apple 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.

7.8%

b.

7.5%

c.

7.1%

d.

8.0%

e.

6.5%