AlgebraVery hardDistance at which a tank runs dry
Algebra practice question
A car's fuel gauge shows 42 litres after 100 kilometres and 30 litres after 250 kilometres, and the fuel level falls linearly with distance. After how many kilometres from the start will the tank be empty?
Answer: 625
The car uses 12 litres per 150 km, or 0.08 litres per km. From 42 litres at 100 km, it can go a further 42/0.08 = 525 km: 625 km in all.
Common wrong answers
- If you answered 150
- 150 is the distance between the two readings.
- If you answered 375
- 375 is how much further the car can go after the 250 km reading, not the total from the start.
- If you answered 525
- 525 is the distance after the 100 km mark, not from the start.
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