State whether the following statements are True or False: 1. The sum of all costs of manufacturing costs except direct materials is called manufacturing overhead. 2. Conversion cost is the sum of direct labor and manufacturing overhead. 3. Prime cost is the sum of direct labor and manufacturing overhead. 4. Thread used in the production of mattresses, an indirect material, is classified as manufacturing overhead. 5. Period costs are also known as inventoriable costs. 6. All costs in a merchandising company are period costs. 7. A variable cost is constant if expressed on a per unit basis but the total dollar amount changes as the number of units increases or decreases. 8. As activity increases within the relevant range, fixed costs remain constant on a per unit basis. 9. Direct costs are often difficult to trace to the specific cost object under consideration. 10. All of the following are examples of opportunity costs: salary given up to start a business; rental income given up when you live in a house you own; interest income that could be earned on money spent for a car