Rogen Corporation manufactures a single product. The standard cost per unit of product is shown below. The predetermined manufacturing overhead rate is $14.00 per direct labor hour ( $21.001.5 ). It was computed from a master manufacturing overhead budget based fixed overhead costs of $61,875 (\$7.50 per hour). Actual costs for October in producing 4,200 units were as follows. The purchasing department buys the quantities of raw materials that are expected to be used in production each month. Raw materials inventories, therefore, can be ignored. The purchasing department buys the quantities of raw materials that are expected to be used in production each month. Raw materials inventories, therefore, can be ignored. (a) Compute the total overhead variance