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
Price
1-250.............. $6.00
250-499........... $5.50
500-999........... $5.00
1,000 or more..... $4.75