1. EOQ Problem - The purchasing manager for Central Valve Company, which sells industrial valves and other fluid-control devices, is in the process of reviewing the inventory policies on their most popular valve called the Western. The demand for the valve has averaged 4,000 units annually. The cost of each valve is $90, and the annual inventory carrying cost per valve is estimated to be 10% of the cost of the valve. The agent has done some studies on the costs involved in placing an order and has concluded that the cost is $25 per order. The company operates for 200 working days per year.
   1. What is the optimal order quantity?
   2. What is the minimum annual cost?
   3. What is the optimal number of days between orders?

How much should the ordering cost reduce by if the company wants to reduce the optimal order quantity in part a. above by half? (use What If in Excel)