Enugu Manufacturing Co. provided the following data: Prime cost ₦350,000; Factory overheads ₦90,000; Opening work-in-progress ₦40,000; Closing work-in-progress ₦55,000. What is the cost of production (cost of goods manufactured)?

Cost of production = Prime cost + Factory overheads + Opening WIP − Closing WIP = ₦350,000 + ₦90,000 + ₦40,000 − ₦55,000 = ₦425,000. Adding closing WIP instead of subtracting gives ₦535,000, a common error. The work-in-progress adjustment accounts for partially completed goods.