Jackson Industries uses a standard cost system in which direct materials inventory is carried at standard cost. Jackson has established the following standards for one unit of product: Standard Quantity Direct materlals Direct labor 6 pounds 2.40 hours Standard Price or Rate $4.30 per pound $5.00 per hour $25.80 $12.00 During May, Jackson purchased 145,600 pounds of direct material at a total cost of $655,200. The total factory wages for May were $275,400, 90 percent of which were for direct labor. Jackson manufactured 21,000 units of product during May using 122,800 pounds of direct material and 50,900 direct labor-hours. The labor rate variance for May is O $6,640 Favorable $5,440 Unfavorable O $6,640 Unfavorable $4,240 Favorable