Suppose that the current $1-$year rate $(1-$year spot rate$)$ and expected $1-$year T$-$bill

rates over the following three years $($i$.$e$.,$ years $2,3,$ and $4,$ respectively$)$ are as

follows:

${?}_1{R}_1=7\%,E{(}_2{r}_1)=8\%,E(3r_1)=8\mathrm{.}50\%,E{(}_4{r}_1)=8\mathrm{.}85\%$

Using the unbiased expectations theory, calculate the current $($long$-$term$)$ rates for

one$-,$ two$-,$ three$-,$ and four$-$year$-$maturity Treasury securities$.$