An outside supplier has offered to supply the electrical parts to the Diehl Company for only $12.05 per part. One-third of the traceable fixed manufacturing cost is supervisory salaries and other costs that can be eliminated if the parts are purchased. The other two-thirds of the traceable fixed manufacturing costs consist of depreciation of special equipment that has no resale value. Economic depreciation on this equipment is due to obsolescence rather than wear and tear. The decision to buy the parts from the outside supplier would have no effect on the common fixed costs of the company, and the space being used to produce the parts would otherwise be idle.