FIXED ORDER QUANTITY SYSTEMS QUESTION ONE: Use of Model I The Call-Us Plumbing Supplying Company stocks thousands of plumbing items sold to regional plumbers, contractors, retailers. Mr. Swartz, the firm's general manager. wonders how much money can be saved annually if EOQ were used instead of the firm's present rules of the thumb. He instructs Mary Ann Church, an inventory analyst, to conduct an analysis of one material only (Material # 3925, a brass valve) to see if significant savings might result from using the EOQ. Mary Ann develops the following estimates from accounting information: D= 10,000 valves per year, Q=400 valves per order (present order quantity). C = $.40 per valve per year, and S= $5.50 per order