Alcoa produces 100-, 200-, and 300-foot-long aluminum ingots for customers. This week's demand for ingots is shown in Table 115.

Alcoa has 4 furnaces in which ingots can be produced. During a week, each furnace can be operated for 50 hours. Because ingots are produced by cutting long strips of aluminum, longer ingots take less time to produce than shorter ingots. If a furnace is devoted completely to producing one type of ingot; the number it can produce in a week is shown in Table 116.

For example, furnace 1 could produce 350 300-foot ingots per week. The material in an ingot costs $10 per foot. If a customer wants a 100- or 200-foot ingot, then she will accept an ingot of that length or longer. How can Alcoa minimize the material costs incurred in meeting required weekly demands?

TABLE 115 Ingot (ft) Demand 100 700 200 300 300 150 TABLE 116 Ingot Length Furnace 100' 200' 300' 1234 230 340 350 2 230 260 280 240 300 310 200 280 300