15. Why are the terms product costs and period costs used to describe manufacturing costs and nonmanufacturing costs? 16. How does the timing of recording expenses differ between product and period costs? 17. Review "Business in Action 1.5" Why are items such as the hull, engine, transmission, carpet, and seats classified as direct materials and items such as glue, paint, and screws classified as indirect materials? 18. Review Business in Action 1.6" Provide two examples of selling costs and two examples of general and administrative costs at PepsiCo 19. Describe the three inventory accounts used to record product costs. 20. What are the three categories of product costs that flow through the work-in-process inventory account? Describe each one. 21. When is the cost of goods sold account (often called cost of sales) used, and how is the dollar amount recorded in this account determined? 22. How does a merchandising company income statement differ from a manufacturing company income statement