Hoy Heating and Air Conditioning Company repairs heating and cooling equipment. Each Obj. 2 time a service technician completes a job, a time sheet is turned in and the job cost is computed. The company calculates the cost of each job by adding the cost of any materials used on the job, the labor cost of the service technician, and an overhead charge to cover administrative and support expenses. Hoy uses an estimated cost of support expenses in its calculation. Why do you think the company uses predetermined rates rather than actual costs in computing the costs of each service call?