What is the standard deviation for Stock A?

What is the standard deviation for Stock B?

\begin{tabular}{cccc} \hline \multicolumn{2}{c}{ COMMON STOCK A } & \multicolumn{2}{c}{ COMMON STOCK B } \\ \hline PROBABILITY & RETURN & PROBABILITY & RETURN \\ \hline 0.20 & 10% & 0.20 & 5% \\ 0.60 & 14% & 0.30 & 7% \\ 0.20 & 20% & 0.30 & 16% \\ & & 0.20 & 21% \\ \hline \end{tabular}