Dear sir, I have a problem regarding the math below- Monthly demand for a product is 10000 units. The purchase price is $10/unit and company’s cost of finance is 15% pa. Warehouse storage costs per unit pa are $2/unit. The supplier charges $200 per order for delivery. Calculate the EOQ. Now, why the holding cost in the ans. is not $2 only but ($10×0.15)+$2 = 3.5 ?