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 21,000 units. However, during March the company actually produced and sold 24,000 units and incurred the following costs: a. Purchased 150,000 pounds of raw materials at a cost of $6.40 per pound. All of this material was used in production. b. Direct laborers worked 66,000 hours at a rate of $18 per hour. c. Total variable manufacturing overhead for the month was $413,820. 1. What is the labor spending variance for March? (Indicate the effect of each variance by selecting "F" for favorable, " U " for infavorable, and "None" for no effect (i.e., zero variance.). Input all amounts as positive values.)