Classify the total costs of each of the following as variable, fixed, mixed, or step. Sales volume is the cost driver.

Overhead costs in the factory for incidental components such as small screws and rivets.
Salary of machine operator who is paid based on number of units produced on the machine
Water consumed by the plant, which is based on a flat fee plus actual consumption
Salaries of quality inspectors when each inspector can evaluate a maximum of 500 units per day
Property taxes
Keyboards purchased from a subcontract supplier in a computer assembly plant
Electric power in a factory
Annual salary for the vice president of manufacturing
Raw materials used in production
Fire insurance on factory building