1. An amount of $15,000 is deposited into an account which pays 5.2% interest.
   1. How many periods will it take the account to grow to at least $20,000 if interest is compounded semiannually?

2. If interest is compounded semiannually and simple interest is paid for part of a period, how long before the account is worth exactly $20,000? Use a 360 day year for the simple interest.

3. If interest is compounded continuously, how long before the account is worth exactly $50,000? Use a 360-day year.