Pierpont Engine Shop uses a job order cost system to determine the cost of perfoming engine repair work. Estimated costs an expenses for the coming period are as follows: Engine parts $ 700,000 Shop direct labor 520,000 Shop and repair equipment depreciation 38,000 Shop supervisor salalries 100,000 Shop property tax 18,000 Shop supplies 13,000 Advertising expense 14,240 Administrative office salaries 60,000 Administrative office depreciation expense 8,000

Total costs and expenses 1,471,240

The average shop direct labor rate is $20 per hour.

Determine the predetermined shop overhade rate per direct labor hour.