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

$($a$)$

Salary of the department manager

Answer $1$

$($b$)$

Memory chips in a computer assembly plant

Answer $2$

$($c$)$

Real estate taxes

Answer $3$

$($d$)$

Salaries of quality inspectors when each inspector can evaluate a

Answer $4$

maximum of $1,000$ units per day

$($e$)$

Wages paid to production employees for the time spent working on products

Answer $5$

$($f$)$

Electric power in a factory

Answer $6$

$($g$)$

Raw materials used in production

Answer $7$

$($h$)$

Automobiles rented on the basis of a fixed charge per day plus an

Answer $8$

additional charge per mile driven

$($i$)$

Sales commissions

Answer $9$

$($j$)$

Straight$-$line depreciation on office equipment