In the quantity discount model in Example 12.2, the minimum total annual cost is region 3 is clearly the best. Evidently, the larger unit purchase costs in the other two regions make these two regions unattractive.

When would a switch take place? To answer this question, change the model slightly. First, change the fixed cost of ordering to $40. Second, keep the unit cost in region 3 at $26, but change the unit costs in regions 1 and 2 to $26  2k and $26  k, where you can let k vary. (Currently, k is $2.) Use SolverTable with k varied over some appropriate range to see how small k must be before it is optimal to order from region 1 or