A cement manufacturer has supplied the following data: Tons of cement produced and 220,000 sold Sales revenue $924,000 Variable manufacturing $297,000 expense Fixed manufacturing expense $280,000 Variable selling and administrative expense $165,000 Fixed selling and administrative $82,000 expense Net operating income $100,000 The company's contribution margin ratio is closest to: 40.0% 50.0% 60.0% 10.7%