The quantity discount model in Example 12.2 uses one of two possible types of discount structures. It assumes that if the company orders 100 units, say, each unit costs $150. This provides a big incentive to jump up to a higher order quantity. For example, the total purchasing cost of 149 units is 149($150) = $22,350, whereas the total cost of 150 units is only 150($140) = $21,000. Change the discount structure so that the first 74 units cost $160, the next 75 units cost $150, and any units beyond 150 cost $140. Now the cost of 75 units, for example, is 49($160) + $150 = $7990. Modify the model to incorporate this structure, and find the optimal order quantity.