How much money will Laura and Marty have to deposit each month, beginning one month after the baby is born and ending when she turns 18, in order to have enough saved up for their childs education. Assume that the yield on investments is 7.2% per year, today's estimated college costs of $21,000 and it is increasing at 3% per year, and that their child will enter college when he or she turns 18 and will complete the degree in 4 years. Note that the investment yield will be about 3% lower after her daughter's admission to a college.