A product of a chemical factory in Riyadh has a demand of 20 tons per day. The capacity for producing the product is 50 tons per day. Set up costs 100 SR, and storage costs are 5 SR per ton a year. The firm operates 200 days a year. a) How many tons per run are optimal? b) Determine the approximate length of a production run? c) How many runs per year would there be? d) What would the average inventory be with this run size?