The standards for direct labour for a product are 2.5 hours at $8 per hour. Last month, 9,000 units pf the product were made, and the labour efficiency variance was $8,000 favourable. What was the actual number of hours worked during the past period? a) 23,500 hours. b) 22,500 hours. c) None of the answers provided is correct d) 20,500 hours. e) 21,500 hours