Welding Plus, a local retailer of welding supplies, faces demand for its 820 High- Intensity Welding Rod at a constant rate of 53,500 units per year. It costs Welding Plus $22.50 to process an order to replenish stock and $1.75 per unit per year to carry the item in stock. Stock is received four working days after an order is placed. No backordering is allowed. Assume 300 working days a year.
What is Welding Plus's optimal order quantity for the 820 rod?