A mother wants to help her child's higher education fund. she wishes to have $15,000 available each year for 6 years. her child starts college in 15 years and she can save 6% before school starts if she puts her end of the year bonus into a trust fund and figures that the fund will earn 4% after her child begins college education. what does she have to put aside annually if the money is withdrawn for the college at the beginning of each year attending college?