The school board for the Bellevue School District has made the decision to purchase 1,350 additional Macintosh com-puters for computer laboratories in all its schools. Based on past experience, the school board also has directed that these com-puters should be purchased from some combination of three companiesEducomp, Macwin, and McElectronics. In all three cases, the companies charge a discounted variable cost per com-puter and a fixed delivery and installation cost for these large sales to school districts. The next table shows these charges as

	Project 1	Project 2	Project 3	Project 4	Project 5
NPV ($million)	12	15	20	9	23
Year 1	8	10	12	4	14
Year 2	14	18	18	7	20
Year 3	17	25	24	9	25
Year 4	0	30	30	0	32

Cumulative Cash Outflow Required ($million)

Each project must be done in full (with the corresponding cash flows for all four years) or not done at all. Furthermore, there are the following additional considerations. Project 1 cannot be done unless Project 2 is also undertaken, and projects 3 and 4 would compete with each other, so they should not both be cho-sen. YCC expects to have the following cash available to invest in these projects: $40 million for year 1, $25 million for year 2, $16 million for year 3, and $12 million for year 4. Any available money not spent in a given year is then available to spend the following year. YCCs policy is to choose their projects so as to maximize their total expected NPV. a. Formulate a BIP model in algebraic form for this problem.