Required information [The following information applies to the questions displayed below] Preble Company manufactures one product. Its variable manufacturing overhead is applled to production based on direct labor-hours and its standard cost card per unit is as follows: The planning budget for March was based on producing and selling 24,000 units. However, during March the company actually produced and sold 30,600 units and incurred the following costs: a. Purchased 170,000 pounds of raw materials at a cost of $9.00 per pound. All of this material was used in production. b. Direct laborers worked 68,000 hours at a rate of $18 per hour. c. Total variable manufacturing overhead for the month was $512,040. 0. What is the labor efficiency varlance for March? (Indicate the effect of each variance by selecting "F" for favorable, "U" for unfavorable, and "None" for no effect (i.e., zero variance.). Input all amounts as positive values.)