Predetermined Factory Overhead Rate Road Runner Engine Shop uses a job order cost system to determine the cost of performing engine repair work. Estimated costs and expenses for the coming period are as follows: Engine parts $1,102,900 Shop direct labor 805,000 Shop and repair equipment depreciation 31,500 Shop supervisor salaries 87,500 Shop property taxes 15,900 Shop supplies 12,100 Advertising expense 22,100 Administrative office salaries 94,800 Administrative office depreciation expense 12,100 Total costs and expenses $2,183,900 The average shop direct labor rate is $23 per hour