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 material: 6 pounds at $8.00 per pound Direct labor: 4 hours at $16.00 per hour Variable overhead: 4 hours at $4.00 per hour $ 48.00 64.00 16.00 Total standard variable cost per unit $ 128.00 The company also established the following cost formulas for its selling expenses: Variable Cost per Unit Sold Fixed Cost per Month $370,000 $ 100,000 Advertising Sales salaries and commissions Shipping expenses $14.00 $ 5.00 The planning budget for March was based on producing and selling 19,000 units. However, during March the company actually produced and sold 24,000 units and incurred the following costs: a. Purchased 160,000 pounds of raw materials at a cost of $7.20 per pound. All of this material was used in production. b. Direct-laborers worked 82,000 hours at a rate of $17.00 per hour. C. Total variable manufacturing overhead for the month was $336,960. d. Total advertising, sales salaries and commissions, and shipping expenses were $380,000, $337,020, and $132,000, respectively. 11. What is the variable overhead rate variance for March? (Do not round intermediate calculations. Input the amount as a positive value. Indicate the effect of each variance by selecting "F" for favorable, "U" for unfavorable, and "None" for no effect (i.e., zero variance.).) Variable overhead rate variance