Winkle, Kotter, and Zale is a small law firm that contains 10 partners and 12 support persons. The firm employs a job order costing system to accumulate costs chargeable to each client, and it is organized into two departments-the Research and Documents Department and the Litigation Department. The firm uses predetermined overhead rates to charge the costs of these departments to its clients. At the beginning of the current year, the firm's management made the following estimates for the year Departmen Research Documents Litigation Research-hours 19.500 Direct attorney-hours 8.700 16,000 Materials and supplies 18.100 5.000 Direct attorney cost S 429.200 800.900 Departmental overhead cost S 682.500 S 320,360 The predetermined overhead rate in the Research and Documents Department is based on research-hours, and the rate in the Litigation Department is based on direct attorney cost. The costs charged to each client are made up of three elements: materials and supplies used, direct attorney costs incurred, and an applied amount of overhead from each department in which work is performed on the case. Case 618-3 was initiated on February 10 and completed on June 30. During this period. the following costs and time were recorded on the case: artment Research and Documents Litigation Research-hours Direct attorney-hours Materials and supplies 50 30 Direct attorney cost $440 2,100 Required: 1-a. Compute the predetermined overhead rate used during the year in the Research and Documents Department. redetermined overhead rate per hour