A deposit of $500 has been made in an interest-bearing account. No withdrawals or other deposits (aside from earned interest) are made for 5 years.

Write an expression to represent the account balance for each of the following situations.

a. 6.5% annual interest calculated monthly
b. 6.5% annual interest calculated every two months
c. 6.5% annual interest calculated quarterly
d. 6.5% annual interest calculated semi-annually