Use the following information:

Stock A B

Good state $10\%14\%$

Bad state $2\%-2\%$

Assume there is $60\%$ probability that the good state occurs and $40\%$ chance the bad state occurs.

What is the standard deviation of stock A$?($Please use $5$ decimal places, this should be written in percentage, so an answer of $23\mathrm{.}143\%$ should be written as $\mathrm{.}23143)$