A watch repair shop buys batteries for a variety of products. The most frequent battery purchase is for a Y300, with demand of 3,000 per year. The order cost is $15 per order, and the holding cost is $0.50 per battery. Given the following price schedule, calculate the optimal order quantity? Number of batteries and price; 1-250 = $6.00, 250-499 = $5.50, 500-999 = $5.00, 1,000 or more = $4.75.