Nil Co. uses a predetermined overhead rate based on direct labour cost to apply manufacturing overhead to jobs. For the year ended December 31, Nil's estimated manufacturing overhead was 600,000, based on an estimated volume of 50,000 direct labour hours, at a direct labour rate of 6.00 per hour. Actual manufacturing overhead amounted to 620,000, with the actual direct labour cost of 325,000. For the year, the manufacturing overhead was: overapplied by 20,000. overapplied by 30,000. underapplied by 30,000 underapplied by 22,000