hapter Chapter 18: Managerial Accounting Concepts and Principles 22. 14. Variable costs are costs that remain constant on a per-unit basis as the level of activity change a. True b. False 15. Direct materials and direct labor costs are examples of variable costs of production. a. True b. False 16. Rental charges of $40,000 per year plus $3 for each machine hour over 18,000 hours is an example of a fixed cost. a. True b. False 17. The contribution margin ratio is the same as the profit-volume ratio. a. True b. False um 600 of sales the contributio