Use the following information to answer the question:

Stock's Expected

State of the Economy	Probability of State Occurring	Return if this state occurs
Boom	0.25	25%
Normal	0.50	15%
Recession	0.25	5%

The expected return is 15%. What is the standard deviation?

a. .06

b. .0816

c. .0707

d. .50

e. none of the above