Koebel Corporation uses a job order cost system with manufacturing overhead applied to products on the basis of direct labor hours For the upcoming year, Koebel Corporation estimated total manufacturing overhead cost at $673,400 and total direct labor hours of 51,800. Koebel Corporation started the year with no beginning balances in either Work in Process Inventory or Finished Goods Inventory. During the year, actual manufacturing overhead incurred was $634,900 and 47,100 direct labor hours were used. Required: a. Calculate the predetermined overhead rate. b. Calculate how much manufacturing overhead will be applied to production. c. Is overhead over- or underapplied? By how much? d. What account should be adjusted for over-or underapplied overhead? Should the balance be increased or decreased? Complete this question by entering your answers in the tabs below. Calculate the predetermined overhead rate