A cement manufacturer has supplied the following data: Tons of cement produced and sold 235,000 Sales revenue $939,000 Variable manufacturing expense $255,000 Fixed manufacturing expense $289,000 Variable selling and administrative expense $120,600 Fixed selling and administrative expense $85,000 Net operating income $189,400 The company's contribution margin ratio is closest to: 42.1% 69.2% 60.0% 20.2%