What Is the Standard Deviation of a Portfolio Which Is

Multiple Choice

What is the standard deviation of a portfolio which is invested 20% in share A,30% in share B and 50% in share C?
$\begin{array}{|l|l|l|l|l|} \hline& & \begin{array}{l}\text { Returns if } \\\text { State } \\\text { Occurs }\end{array}& &{} \\\hline \text { State of Economy } & \text { Probability of State of Economy } & \text { ShareA } & \text { ShareB } & \text { Share C } \\\hline \text { Boom } & 10 \% & 15 \% & 10 \% & 5 \% \\\hline \text { Normal } & 70 \% & 9 \% & 6 \% & 7 \% \\\hline \text { Recession } & 20 \% & -14 \% & 2 \% & 8 \%\\\hline\end{array}$

A) 0.6%
B) 0.9%
C) 1.8%
D) 2.2%
E) 4.9%