Required information [The following information applies to the questions displayed below.] 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: 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 incurted 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 hout. c. Total variable manufacturing overhead for the month was $512,040. 14. What is the variable overhead rate variance for March? (Round the actual overhead rate to two decimal places. Indicate the effect of each variance by selecting "F" for favorable, " W " for unfavorable, and "None" for no effect (Le., zero variance.). Input all amounts as positive values.)