You Have a Portfolio Which Is Comprised of 30% of Stock

Multiple Choice

You have a portfolio which is comprised of 30% of Stock A and 70% of Stock B. What is the portfolio standard deviation?
$\begin{array}{lllr}\text { State of the Economy } & \text { Probability } &\text {E(R) }_{A}&\text { E(R) }_{B}\\&&30\%&70\%\\\\\text { Boom }&.15&20\%&14\%\\\text { Normal } & .75 & 11\% & 9 \% \\\text { Recegsion } & .10& -23 \% & -5 \%\end{array}$

A) 4.00%
B) 5.56%
C) 6.68%
D) 6.82%
E) 7.47%