Barbie's trading company sells Barbie's doll and the annual demand is 2800 doll.It costs the company $33 to place an order and the carrying cost is 7% of the unit cost.The cost of each doll is $40.The supplier offers the following discounts to Barbie's Company. Order Quantity < 100 Discount None 4% Unit Cost $40 $38 100 quantity < 200 200 8% $37.20 a) What would be the optimal order quantity? b) What is the minimum annual inventory cost? (18 marks) (2 marks)