SOLUTION
E20-21 Determining total mixed cost
Learning Objective 1
17,000 gal. $42.25
Robert Street Barber Shop pays $30 per month for water for the first 10,000 gallons and $1.75 per
thousand gallons above 10,000 gallons. Calculate the total water cost when the barber shop uses 6,000
gallons, 12,000 gallons, and 17,000 gallons.
SOLUTION
($1.75 per 1,000 gal. × Water usage above 10,000 gal. ) + $30
($1.75 per 1,000 gal. × 0 ) + $30
($1.75 per 1,000 gal. × 7,000 gal. ) + $30
E20-22 Determining mixed costs—the high-low method
Learning Objective 1
3. $4,300
The manager of Quick Car Inspection reviewed the monthly operating costs for the past year. The costs
ranged from $4,400 for 1,400 inspections to $4,200 for 1,000 inspections.
Requirements
1. Calculate the variable cost per inspection.
2. Calculate the total fixed costs.
3. Write the equation and calculate the operating costs for 1,200 inspections.
4. Draw a graph illustrating the total cost under this plan. Label the axes, and show the costs at 1,000,
1,200, and 1,400 inspections.