One-year treasury bills currently earn 1.8 percent. You expect that one year from now, 1-year treasury bill rates will increase to 2.00 percent.

One-year treasury bills currently earn 1.8 percent. You expect that one year from now, 1-year treasury bill rates will increase to 2.00 percent. If the unbiased expectations theory is correct, what should the current rate be on 2-year treasury securities?

I don't just need help with the formula, but also how to calculate the answer in Excel once I have the formula.

Thank you!