Given the following information, what is the standard deviation of a portfolio which is invested $30$ percent in stock $A,20$ percent in stock $B,$ and $50$ percent in stock $C?$

$\backslash$table$[[$State of$,$Probability of$,,$Rate of Return if State Occurs$],[$Economy$,$State of Economy,Stock A$,$Stock B$,$Stock C$,],[$Boom$,\mathrm{.}10,\mathrm{.}22,\mathrm{.}08,\mathrm{.}18,],[$Normal$,\mathrm{.}90,\mathrm{.}08,\mathrm{.}14,\mathrm{.}07,]]$

$8\mathrm{.}99$ percent

$6\mathrm{.}67$ percent

$7\mathrm{.}69$ percent

$2\mathrm{.}55$ percent

$10\mathrm{.}37$ percent