Question

You're going on a 1211-mile trip, and your car gets about 29 miles per gallon. Gas prices along your route average $3.40. Estimate the cost of gasoline for this trip by rounding the distance to 1200 miles, the mileage to 30 miles per gallon, and the cost of gas to $3.00 per gallon. Calculate the answer without using estimate and compare the two results. (Round your answers to the nearest cent.)

Answer 1

Using the estimate:

The car has to go for 1,200 miles but it consumes a gallon of gasoline for every 30 miles. The number of gallons it will need is therefore:

= 1,200 / 30

= 40 gallons

Each gallon costs $3.00 so the total cost is:

= 40 * 3

= $120

Without using the estimate:

The car has to go for 1,211 miles but it consumes a gallon of gasoline for every 29 miles. The number of gallons it will need is therefore:

= 1,211 / 29

= 41.76 gallons

Each gallon costs $3.40 so the total cost is:

= 41.76 * 3.40

= $‭141.98

Using the estimate provides a lower cost of gasoline for the trip.