Given the following information, what is the standard deviation $($in percent$)$ of the returns on this stock? Carry intermediate calculations to at least five decimals. Answer to two decimals

$\backslash$table$[[$State of Economy,$\backslash$table$[[$Probability of State of$],[$Economy$]],$Rate of Return $(\%)],[$Recession$,15\%,-14\mathrm{.}76],[$Normal$,60\%,19\mathrm{.}4],[$Boom$,25\%,20\mathrm{.}93]]$