4. A discount store has been given a quantity discount schedule for toy cars. The quantity schedule is shown as follows (Table 1). The annual demand is 6,000 cars, the ordering cost is $50 per order and inventory carrying charge, as a percent of cost, is 30%. (The result obtained in each step should be rounded to an integer number. For example, 8.23 should be rounded to 8, and 8.51 should be rounded to 9.) Table 1. The quantity discount schedule Discount Discount Discount Price (P) Number Quantity 1 0 to 1499 AU$6.00 2 1,500 to 2,999 AU$5.40 3 3,000 and over AU$5.30 (a) Calculate the optimal order quantity for each discount offer. (3 marks) (b) Calculate the total inventory cost for each discount offer. (3 marks) (c) What order quantity should the store order to minimize the total inventory cost? What is the managerial implication of the optimal solution