Question

As part of your physics class, you calculated your automobile’s average fuel usage over a short interval of time and found it to be 28 MPG. If you drive an average of 120 miles per week and the cost of gasoline averages $2.75 per gallon, how much do you spend per year on gasoline?

Answer 1

If you drive 120 miles per week then you spend $\dfrac{120}{28} = \dfrac{30}{7}$ gallons of fuel per week. Then, during a year you will spend $\dfrac{30}{7}\times \dfrac{365}{7} =\dfrac{10950}{49}$ gallons (there are $365/7$ weeks in a year). Then, the price will ge:

$$p = \dfrac{10950}{49} \times \$2.75 \approx \$614.54$$

Answer. $614.5.