need help future value

Find the future values of the following ordinary annuities: a. FV of $800 paid each 6 months for 5 years at a nominal rate of 11% compounded semiannually. Do not round intermediate calculations. Round your answer to the nearest cent $ b. FV of $400 paid each 3 months for 5 years at a nominal rate of 11% compounded quarterly. Do not round intermediate calculations. Round your answer to the nearest cent S c. These annuities receive the same amount of cash during the 5-year period and earn interest at the same nominal rate, yet the annuity in part b ends up larger than the one in part a. Why does this occur