How much would I spend in a week if I average 25 km/day, get a mileage of 30 miles per US gallon, and petrol costs €1.26/L with a conversion rate of €1= $1.26?
1 Answer
Jun 21, 2014
You would spend $95.10.
You use a series of conversion factors.
There are many conversions, so let's break it into parts.
Calculate the gallons used
1 week ×
18.123 gal (three significant figures plus two guard digits)
Calculate the cost
18.123 gal ×
The answer has only three significant figures, so it is precise only to the nearest
10 ¢.
Notice how the conversion factors are set up so they cancel to give the desired units at the end.