i feel like this is super easy but for some reason i'm not getting it correct, but if i had to backsolve for this question how would i do that. like say i wasn't given 7%

Question 3 1-year T-bill at beginning of year 1: 6% 1-year T-bill at beginning of year 2: 7% 1-year T-bill at beginning of year 3.9% 1-year T-bill at beginning of year 4: 1 1% Using the expectations hypothesis theory for the term structure of interest rates, determine the expected return for securities with maturities of two, three, and four years. 2-year 3-year 4-year (600 + 796)/2-6. 5% (690 + 700 + 9%)/3-7.33% (600 + 790 + 9% + 1 %)/4-8.25%