Q: I traveled home in an old car that was leaking gas and could only be driven at a steady 30 miles per hour while getting gas mileage of 20 miles per gallon. At the start of the trip, there were exactly 10 gallons of fuel but the fuel tank lost fuel at the rate of half a gallon per hour. Just as I arrived home, the car stopped because it had run out of fuel and I had only just made it. How far did I drive?
A: 150 miles
Solution: 30 mph with 20 miles per gallon means that 20 miles would use 1 gallon so 30 miles uses 1.5 gallons/hour and we must also include the 1/2 gallon an hour due to the leak.
So the gas level is decreasing by a rate of 2 gallons per hour which means that the 10 gallons will last for 5 hours.
5 hours at the steady 30 mph = 150 miles
So the gas level is decreasing by a rate of 2 gallons per hour which means that the 10 gallons will last for 5 hours.
5 hours at the steady 30 mph = 150 miles
