Sarah deposits $5,000 in her savings account every 3 months. Determine the account balance after 7 years (28 deposits) in the following three situations:

1. The nominal annual interest rate paid by the account is 12%, compounded quarterly, i.e., every 3 months.

2. The nominal interest rate is 12% APR (annual rate, compounded monthly).

3. The nominal annual interest rate paid by the account is 12%, compounded bi-annually,

   i.e., every 6 months.