Sheffield Corporation manufactures a single product. The standard cost per unit of product is shown below. The predetermined manufacturing overhead rate is $14 per direct labor hour ( $35.00+2.50). It was computed from a master manufacturing overhead budget based on normal production of 13,250 direct labor hours (5,300 units) for the month. The master budget showed total variable costs of $92,750 (\$7.00 per hour) and total fixed overhead costs of $92.750($7.00 per hour). Actual costs for October in producing 3,900 units were as follows. The purchasing department buys the quantities of raw materials that are expected to be used in production each month. Raw materiais 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. Total overhead variance \$