Analyze an environmental problem doing calculations

Commuting and fuel economy

Units 6 and 7
10 points
About 24 minutes

You can use a calculator on this question, just like on exam day.

You work through an environmental scenario using numbers: set up and solve calculations (showing your work), then explain the science and propose solutions. Several of the 10 points come from the calculations, usually one for the setup and one for the answer. On the exam: Question 3 of 3 in the 70-minute free-response section (Section II is 40% of the exam score).

The question

In a city, 40,000 people drive alone to work. Each commuter drives a round trip of 30 km per workday for 250 workdays per year, in a car that averages 12 km per liter of gasoline. Burning 1 liter of gasoline releases 2.3 kg of carbon dioxide (CO₂). (1 metric ton = 1,000 kg)

Suggested time: 24 minutes

Your answers are saved in this browser as you type.

Part (a)

2 points

Calculate the volume of gasoline, in liters, that one commuter uses for commuting in one year. Show your work.

Your answer to part (a)

0 / 2,500 characters

Part (b)

2 points

Calculate the mass of CO₂, in metric tons, that one commuter releases from commuting in one year. Show your work.

Your answer to part (b)

0 / 2,500 characters

Part (c)

2 points

Suppose 6,000 of the commuters replace their cars with hybrid cars that average 20 km per liter. Calculate the total volume of gasoline, in liters, saved each year. Show your work.

Your answer to part (c)

0 / 2,500 characters

Part (d)

1 point

Explain one reason a hybrid car gets better fuel economy than a conventional gasoline car.

Your answer to part (d)

0 / 2,500 characters

Part (e)

1 point

Identify one primary air pollutant, other than CO₂, released in car exhaust.

Your answer to part (e)

0 / 2,500 characters

Part (f)

1 point

Describe how Corporate Average Fuel Economy (CAFE) standards reduce gasoline use.

Your answer to part (f)

0 / 2,500 characters

Part (g)

1 point

Propose one realistic action the city could take, other than encouraging hybrid cars, to reduce the gasoline used for commuting.

Your answer to part (g)

0 / 2,500 characters

Checking scoring…

Scoring it yourself shows you the rubric, examples and a model answer. Try writing your answer first.