A reactor can only run on one setting for the entire year. How can they meet its annual demand at a minimum cost?

*Formulate* an integer program.

(Based on Boykin [20]) A chemical production company annually produces 500 million pounds of the chemical maleic anhydride using four different reactors. Each reactor can be run on only one of the four settings. The following table gives the annual cost (thousands of dollars) and production (in millions of pounds) for each reactor and each setting. Pounds Reactor 1 Setting Cost 1 70 2 90 3 120 4 160 AN 75 120 150 205 Setting Cost Pounds Reactor 2 1 2 55 80 110 150 3 4 60 100 135 190 Reactor 3 1 2 3 4 80 100 140 180 90 140 175 225 Reactor 4 1 2 3 4 40 70 90 110 50 90 110 150