1. You deposit $20,000 today. If it grows to $60,000 in 10 years, what rate of interest must have your earned?

2. Today is T=0. If you make five annual deposits into a bank account that pays interest at the rate of 6%, how large must the deposits be if the account is worth $75,000 at the end of the fifth year (T=5) and the first deposit is made today?
3. You will start college on your 18^th birthday. Your parents need $100,000 on that day. How much should they deposit into a bank account at the moment of your birth if the bank pays interest at the rate of 9%?