A $7-$year municipal bond yields $4\mathrm{.}80\%.$ Your marginal tax rate $($including state and federal taxes$)$ is $36\mathrm{.}00\%.$ What interest rate on a $7-$year corporate bond of equal risk would provide you with the same after$-$tax return? $($Round your final answer to two decimal places.$)$

$9\mathrm{.}30\%$

$6\mathrm{.}45\%$

$7\mathrm{.}50\%$

$6\mathrm{.}08\%$

$9\mathrm{.}08\%$