Suppose the $4-$year Treasury bonds yield $6\mathrm{.}50\%$ while $7-$year T$-$bonds yield $6\mathrm{.}80\%.$ Assuming the pure expectations

theory is correct, and thus the maturity risk premium for T$-$bonds is zero, what is the yield on a $3-$year T$-$bond expected to

be four years from now?