Preble Company manufactures one product. Its variable manufacturing overhead is applied to production based on direct labor-hours and its standard cost card per unit is as follows: Direct materials: 5 pounds at $11 per pound Direct labor: 3 hours at $12 per hour Variable overhead: 3 hours at $7 per hour Total standard cost per unit $ 55 36 21 $ 112 The planning budget for March was based on producing and selling 21,000 units. However, during March the company actually produced and sold 26,600 units and incurred the following costs: a. Purchased 154,000 pounds of raw materials at a cost of $9.50 per pound. All of this material was used in production. b. Direct laborers worked 63,000 hours at a rate of $13 per hour. c. Total variable manufacturing overhead for the month was $510,930. 15. What is the variable overhead efficiency variance for March? (Round the actual overhead rate to two decimal places. Indicate the effect of each varlance by selecting "F" for favorable, "U" for unfavorable, and "None" for no effect (l.e., zero varlance.). Input all amounts as positive values.) Variable overhead efficiency variance