5. How are quantity discounts evaluated when using the classical EOQ model? The classical EOQ model assumes the per-unit material price is fixed. The quantity discount condition invalidates the total cost curve in Figure 5.7c. Quantity discounts induce a discontinuous total cost curve. Assuming the discount applies to all units (and not just incremental units beyond the discount point), the minimum total cost point will be either at the point of discontinuity or at the traditional EOQ point compared with the original price