A foundry is developing a long-range strategic plan for buying scrap metal for its operations. The foundry can buy scrap metal in unlimited quantity from two sources: Atlanta and Birmingham, and it receives the scrap daily by railroad cars.The scrap is melted down, and lead and copper are extracted. Each railroad car from Atlanta yields 1 ton of copper and 1 ton of lead, and costs $10,000. Each railroad car from Birmingham yields 1 ton of copper and2 tons of lead, and costs $15,000. The foundry needs at least 4 tons of lead and at least 2.5 tons of copper per day for the foreseeable future.

1. In order to minimize the long-range scrap metal cost, how many railroad cars of scrap should be purchased per day from each source? Solve the problem graphically

2. What would be the change in the formulation if the foundry needed exactly 2.5 tons of copper per day? What if they needed no more than 2.5 tons per day?