Following is a list of various costs incurred in producing frozen pizzas. With respect to the production and sale of frozen pizzas, classify each cost as either variable, fixed, or mixed.
1. Property insurance premiums, $1,500 per month plus $0.005 for each dollar of property over $3,000,000
2. Packaging
3. Hourly wages of inspectors
4. Pension cost, $0.50 per employee hour on the job
5. Hourly wages of machine operators
6. Rent on warehouse, $5,000 per month plus $5 per square foot of storage used
7. Refrigerant used in refrigeration equipment
8. Pepperoni
9. Dough
10. Tomato paste
11. Property taxes, $50,000 per year on factory building and equipment
12. Electricity costs, $0.08 per kilowatt hour
13. Salary of plant manager
14. Straight-line depreciation on the production equipment
15. Janitorial costs, $3,000 per month