The annual demand for a product has been projected at 2,000 units. this demand is assumed to be constant throughout the year. the ordering cost is $20 per order, and the holding cost is 20 percent of the purchase cost. currently, the purchase cost is $40 per unit. there are 250 working days per year. whenever an order is placed, it is known that the entire order will arrive on a truck in 6 days. how many units should the company order each time an order is placed if the company wishes to minimize total inventory cost?