Darling Company, which applies overhead to production on the basis of machine hours, reported the following data for the period just ended: Actual units produced: 12,000 Actual variable overhead incurred: $730,000 Actual machine hours worked: 60,000 Budgeted fixed overhead $72,000 Planned level of machine-hour activity 50,000 If Darling estimates four hours to manufacture a completed unit, the company's standard fixed overhead rate per machine hour would be?