An investor wants to find the duration of$$ a$($n$)25-$year, $7\%$ semiannual$$ pay, noncallable bond$$ that's currently priced in the market at $$$$802\mathrm{.}38,$ to yield $9\%.$ Using a $150$ basis point change in$$ yield, find the effective duration of this bond $($Hint$$: use Equation$11\mathrm{.}11).$