Rocky Mountain Tire Center sells 15,000 ?go-cart tires per year. The ordering cost for each order is ?$40, and the holding cost is 30?% of the purchase price of the tires per year. The purchase price is ?$21 per tire if fewer than 200 tires are? ordered, ?$18 per tire if 200 or? more, but fewer than 8,000?, tires are? ordered, and ?$16 per tire if 8,000 or more tires are ordered. How many tires should be ordered each time an order is placed?
a. Rocky Mountains optimal order quantity is ?
b. Total annual cost of ordering optimal order size is ?