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

Salary of the department manager Memory chips in a computer assembly plant Real estate taxes Salaries of quality inspectors when each inspector can evaluate a maximum of 1,000 units per day Wages paid to production employees for the time spent working on products Electric power in a factory Raw materials used in production Automobiles rented on the basis of a fixed charge per day plus an additional charge per mile driven Sales commissions Depreciation on office equipment