Your goal is to have $20,000 in your bank account by the end of four years. If the interest rate remains constant at 6% and you want to make annual identical deposits, how much will you need to deposit in your account at the end of each year to reach your goal?

If your deposits were made at the beginning of each year rather than at the end, by how much would that amount of your deposit change if you still wanted to reach your goal of $20,000 in your bank account, by the end of fours year?