Mark Corporation produces two models of calculators. The Business model sells for $50, and the Math model sells for $30. The variable expenses are given below:

	Business Model	Math Model
Variable production costs per unit	$20	$21
Variable selling and administrative expenses per unit	$ 5	$ 2

The fixed expenses are $74,000 per month. The expected monthly sales of each model are: Business, 2,100 units; Math, 1,600 units.

The contribution margin ratio for the Business model is: (Do not round intermediate calculations.)

60%

30%

50%

70%