A $100,000$ bond is issued with the annual coupon with the rate $9\%$ per annum. The bond is redeemable at $110\%$ of par after $15$ years. On the issue date the bond is purchased for $80,000$ by an investor who is liable to income tax at the rate of $40\%$ and to capital gains tax at the rate of $30\%.$ Find the investor's net effective annual yield for this bond.

Ans: $7\mathrm{.}737\%$