What is the standard deviation of an efficient portfolio with a $19\mathrm{.}0-$percent expected rate of return, given that RF is $4\mathrm{.}0$ percent, ER

$7\mathrm{.}0$ percent, and ${}_M$ is $23\mathrm{.}0$ percent?

$105\mathrm{.}00$ percent

$115\mathrm{.}00$ percent

$52\mathrm{.}17$ percent

$230\mathrm{.}00$ percent