You have 1/2 of your money in stock A and 1/2 of your money in stock B. 1/3 of the time stock A earns 10% and stock B earns 9%. 1/3 of the time stock A earns 8% and stock B earns 7%. 1/3 of the time stock A earns -8% and stock B earns -7%. What is your portfolio standard deviation?

choices:

7.59%

7.23%

7.40%

7.09%