$($Yield to maturity$)$ A bond's market price is $$800.$ It has a $$1,000$ par value, will mature in $10$ years, and has a coupon interest rate of $12$ percent annual interest, but makes its interest payments semiannually. What is the bond's yield to maturity? What happens to the bond's yield to maturity if the bond matures in $20$ years? What if it matures in $5$ years?

a$.$ The bond's yield to maturity if it matures in $10$ years is $\%.($Round to two decimal places.$)$