Elsa's parents start saving for her college education. She will begin college when she turns 18 and will need $50,000 at that time and on each of her following 3 birthdays. Her parents will make a deposit at the end of this year in an account which pays 9 percent compounded annually and an identical deposit at the end of each year with the last deposit occurring when she turns 18. If an annual deposit of $13,560 will allow them to reach their goal, approximately how old is your sister now?