Biery Corporation makes a product with the following standard costs: Standard Quantity or Hours Standard Price or Rate 1.3 liters $6.00 per liter Direct materials 0.6 hours Direct labor $19.00 per hour Variable overhead 0.6 hours $3.00 per hour The company produced 4100 units in April using 5,380 liters of direct material and 2,610 direct labor-hours. During the month, the company d 6,000 liters of the direct material at purchased $5.80 per liter. The actual direct labor rate was $19.80 per hour and the actual variable overhead rate was $2.90 per hour. The company applies variable overhead on the basis of direct labor-hours. The direct materials purchases variance is computed when the materials are purchased. The variable overhead efficiency variance for April is: O $435 F O $435 U $450 O $450 F