Sunshine Corp. uses a predetermined overhead rate of $18 per direct labor hour, which is based on estimated total manufacturing cost of $457, 200 and an estimated activity level of 25,400 direct labor hours. Sunshine actually incurred $447,800 of manufacturing overhead and 24,000 direct labor hours. The amount of over- or under-applied manufacturing overhead for the period was OA $15,800 over-applied $9,400 under-applied $15,800 under-applied OB OD $9,400 over-applied