Compute the standard deviation given these four economic states, their likelihoods, and the potential returns:

Economic State	Probability		Return
Fast Growth	0.20		100	%
Slow Growth	0.50		10	%
Recession	0.20		1	%
Depression	0.10		10	%

a)12.19 percent

b)23.8 percent

c)38.65 percent

d)88.06 percent