An appliance manufacturer purchases the tub portion of washing machines from a supplier with these prices: less than 500, $20 each; 500-999, $19 each; 1,000-1,399, $18 each; 1,400-1,999, $17 each; and 2,000 or more, $16 each. Order costs are $30 per order, annual demand is 10,000 tubs, and holding costs are 30 percent of purchase cost. Determine the order quantity that will minimize total cost.