engineering activity has 1,000 hours of unused capacity. If there is a special order that requires 500 engineering hours, the cost of engineering would be irrelevant. The order can be filled using unused engineering capacity, and the resource spending is the same for each alternative ($250,000 will be spent whether or not the order is accepted). However, if a change in demand for the activity requires a change in resource supply, then the activity cost will be relevant to the decision. This change in cost can occur in one of two ways: (l) he demand for the resource exceeds the supply resource spending), or (2) the demand for the resource drops permanently and supply exceeds demand enough so that activity capacity can be reduced (decreases resource spending To illustrate the first change, suppose that the special order requires 1,500 engineering hours. This exceeds the unused capacity of 1,000 hours. To meet the demand, the organization would need hire a sixth engineer or perhaps use a consulting engineer. Either way, spending on engineering increases if the order is accepted: the cost of engineer is now a relevant cost