. (10 points) A steel rolling mill can produce I-beams at the rate of 60,000 tons per year. Annual customer demand for the beams is 30,000. For each production run of I-beams, the mill must go through a setup that costs $20,000. I-beams cost the mill $3000 per ton, and the mill has an annual holding cost of 20%. a. What is the optimal production batch size for I-beams