Sheridan Co. produces wooden boxes. The company's standards per box require 5 boards, each costing $10 per board, and half of an hour of direct labour. The standard labour rate is $16 per hour. In August, Sheridan Co. purchased 11940 boards for a total cost of $123500. It used 11550 boards to manufacture 1900 boxes. Total labour hours were 1040 hours, and total labour costs were $16260. What was the material quantity variance for August? $20500U$20500F$3900F$3900U