Suppose that the current one-year rate and expected one-year T-bill rates over the following three years (i.e., year 2, 3, and 4, respectively) are as follows:

₁R₁ = 5%, E(₂r₁)=6%, E(₃r₁)= 7%, E(₄r₁)=7.5%

Using the unbiased expectations theory, calculate the current rates for three-year and four-year Treasury securities.