An investor wants to find the duration of a(n) 20-year, 6% semiannual pay, noncallable bond that's currently priced in the market at $723.98, to yield 9%. Using a 100 basis point change in yield, find the effective duration of this bond (Hint: use Equation 11.11)

Equation 11.11 BP (...) - BPD ED = 2 X BP x ar where BP(1.1) = the new price of the bond if market interest rates go up BP (1,1) the new price of the bond if market interest rates go down BP the original price of the bond = the change in market interest rates