Identify whether each of the following is best described as a fixed, variable, or mixed cost with respect to product units. 1. Electricity used in factory building. 2. Wages of an assembly-line worker paid on the basis of acceptable units produced. 3. Cameras used in making smartphones. 4. Insurance on factory building. 5. Rubber used to manufacture athletic shoes. 6. Depreciation expense on equipment (straight-line). 7. Packaging expense