Problem $3-36($LG $3-7)$ The answers in the picture are wrong

Consider the following.

a$.$ What is the duration of a four$-$year Treasury bond with a $10$ percent semiannual coupon selling at par?

b$.$ What is the duration of a three$-$year Treasury bond with a $10$ percent semiannual coupon selling at par?

c$.$ What is the duration of a two$-$year Treasury bond with a $10$ percent semiannual coupon selling at par?

$($For all requirements, do not round intermediate calculations. Round your answers to $2$ decimal places. $($e$.$g$.,32\mathrm{.}16))$

Answer is complete but not entirely correct.