Question

Assume there are 120 million passenger cars in the united states and the average fuel consumption is 20 mi/gal of gasoline. if the average distance traveled by each car is 12,000 mi/yr, how much gasoline would be saved per year if average fuel consumption could be decreased to 25 mi/gal?

Answer 1

Using the given assumptions, the average fuel consumption per year is ...

`\displaystyle \left(1.20\cdot 10^(8)\,\text{cars}\right)*\frac{1\,\text{gal}}{20\,\text{mi}}*\frac{1.2\cdot 10^(4)\,\text{mi}}{1\,\text{yr}\cdot \text{car}}=7.2\cdot 10^(10)\,\frac{\text{gal}}{\text{yr}}`

If gasoline consumption were reduced to 25 mi/gal, this would become

`\frac{1.44\cdot 10^(12)\,\text{gal}}{0.25\cdot 10^(2)\,\text{yr}}=5.76\cdot 10^(10)\,\frac{\text{gal}}{\text{yr}}`

The amount of gasoline saved is the difference of these two values,

`(7.20-5.76)\cdot 10^(10)\,\frac{\text{gal}}{\text{yr}}=1.44\cdot 10^(10)\,\frac{\text{gal}}{\text{yr}}`