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 \begin{tabular}{ll} \hline Sales (4,100 units) & $65,600 \\ Cost of goods sold: & \\ Cost of goods manufactured (4,800 units) & $52,800 \\ Inventory, April 30 (700 units) & (7,700) \\ Total cost of goods sold & $20,500(45,100) \\ Gross profit & $9,350(11,150) \\ Selling and administrative expenses & \\ Operating income & \end{tabular} Joplin Company Variable Costing Income Statement For the Month Ended April 30 Sales Variable cost of goods sold: Variable cost of goods manufactured Inventory, April 30 Total variable cost of goods sold Manufacturing marqin Variable selling and administrative expenses Contribution marqin Fixed costs: Fixed manufacturing costs Fixed selling and administrative expenses Total fixed costs Operating income