3. A firm's requirement of materials is 3,000 units (price *20 per unit) for 6 days. The ordering cost per order is 30 and the carrying cost is 0.50. If the schedule of discount given below is applicable to the firm, determine the most economical order quantity.

Lot Size -499 Discount Rate none 1% 500-699 700-999 2% 1000 2,499 4% 2500 and above 7%