4. Sam wants to save money to meet two objectives. First, he would like to buy a fishing boat 5 years from today at an estimated cost of $15,000. Second, he would like to retire 20 years from now and have a retirement income of $50,000 per year for at least 20 years. Sam can afford to save only $10,000 per year for the first 10 years. He expects to earn 8% per year on average from his savings over the next 40 years. What must his minimum yearly savings be for the second 10 years to meet his objectives?