For 20 years all applicants for jobs as technicians at EquipCorp were required to demonstrate that they could operate and repair the machinery that was central to EquipCorp's manufacturing business. Now, however, that particular machinery is obsolete, and very different machinery fills the central role. Therefore, the old requirement is no longer a useful method for evaluating whether applicants for jobs as technicians at EquipCorp have the skills necessary for the job.