A cement manufacturer has supplied the following data: Tons of cement produced and sold 300,000 Sales revenue $1,004,000 Variable manufacturing expense $237,000 Fixed manufacturing expense $328,000 Variable selling and administrative expense $134,480 Fixed selling and administrative expense $98,000 Net operating income $206,520 The company's contribution margin ratio is closest to: 43.7% 63.0% 67.3% 20.6%