4. Derf Corporation uses a standard cost system in which it applies manufacturing overhead on the basis of standard direct labor-hours. Two direct labor-hours are required for each unit produced. The denominator activity was set at 5,300 units. Manufacturing overhead was budgeted at $143,100 for the period; 20 percent of this cost was fixed. The 9,720 hours worked during the period resulted in production of 4,755 units. Variable manufacturing overhead cost incurred was $114,980 and fixed manufacturing overhead cost was $29,820. The fixed manufacturing overhead volume variance for the period was: O $1,200 Unfavorable O $2.943 Unfavorable $4,143 Unfavorable O$1,472 Unfavorable