On April 30, the end of the first month of operations, Joplin Company prepared the following income statement, based on the absorption costing concept: Joplin Company Absorption Costing Income Statement For the Month Ended April 30 Sales (3,600 units) $64,800 Cost of goods sold: Cost of goods manufactured (4,200 units) $54,600 Inventory, April 30 (600 units) (7,800) Total cost of goods sold Gross profit Selling and administrative expenses Operating income (46,800) $18,000 (10,190) $7,810