An international graduate student will receive a $28,000 foundation scholarship and reduced tuition. He must pay $1,500 in tuition for each of the autumn, winter, and spring quarters, and $500 in the summer. Payments are due on the first day of September, December, March, and May, respectively. Living expenses are estimated to be $1,500 per month, payable on the first day of the month. The foundation will pay him $18,000 on August 1, and the remainder on May 1. To earn as much interest as possible, the student wishes to invest the money. Three types of investments are available at his bank: a 3-month CD, earning 0.75% (net 3-month rate); a 6-month CD, earning 1.9%; and a 12-month CD, earning 4.2%. Develop a linear optimization model to determine how he can best invest the money and meet his financial obligations.