Florida Company $($FC$)$ and Minnesota Company $($MC$)$ are both service companies. Their stock returns for the past three years were as follows: FC: $12$ percent, $21$ percent, $21$ percent; MC: $15$ percent, $15$ percent, $27$ 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.$)$