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

1R1 = 4.0%,E(2R1) = 2.5%,E(3R1) = 10.0%,E(4R1) = 12.0%,

Using the unbiased expectations theory, what is the current (long-term) rate for four-year-maturity Treasury securities ( 1 R 4 )?