Florida Company $($FC$)$ and Minnesota Company $($MC$)$ are both service companies. Their stock returns for the past three years were as follows: FC: $18$ percent, $26$ percent, $22$ percent; MC: $21$ percent, $21$ percent, $33$ percent. What is the standard deviation of a portfolio with $50$ percent of the funds invested in FC and $50$ percent in MC$?($Ignore the correction for the loss of a degree of freedom set out in the text.$)$

Multiple Choice

$14\mathrm{.}4$ percent

$18\mathrm{.}2$ percent

$10\mathrm{.}1$ percent

$11\mathrm{.}4$ percent