You decide to invest in a portfolio consisting of $21$ percent Stock X$,48$ percent Stock Y$,$ and the remainder in Stock Z$.$ Based on the following information, what is the standard deviation of your portfolio?

$\backslash$table$[[$State of$,$Probability of State,Return if Stat$],[$Economy$,$of Economy,Stock X$,$Stock Y$],[$Normal$,\mathrm{.}84,10\mathrm{.}20\%,3\mathrm{.}60\%$