Finally, a relevant image.

This week, I posed to you this conundrum:

A fire engine travels 6 miles to a fire at a speed of 30 mph. Its tank holds 500 gallons of water but has been leaking throughout the journey at a rate of 25 gallons per hour. The fire engine will need 496 gallons of water to put out the fire; by how many gallons will it be short?

So, how many? Answers after the break!

Working this out is actually fairly simple.

The first step is to work out how long the fire engine is moving for. We know it travels 6 miles at 30 mph, and so it must therefore be traveling for 12 minutes to cover that distance, which is **1/5 of an hour**.

Next, we know that the water is lost at 25 gallons per hour. Therefore, we can do 25/5 (since the fire engine travels for 1/5 of an hour) to get a total of **5 gallons lost**.

Finally, we are told that the engine will require 496 gallons to put the fire out, and that it starts with 500. If it loses 5 gallons, it therefore has 495 left when it arrives, which as you can see is just **one gallon short**!

Well, that might have been pretty unlucky for the fire crew but perhaps you were luckier in working the answer out? How’d you do?

Vel.

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June 21, 2010 at 9:25 pm

I was surprised on how little water they actually lost. 25 gallons per hour sounds rather impressive.

I also liked how you could solve this one on scratch paper and not have to use a calculator. 🙂 Even if I second guess my math all the time when I don’t use one. XD

I think if you were one gallon of water short for putting out a fire, you could probably stomp out the rest. At least that’s what I hope they did, in this fictional tale!

June 21, 2010 at 11:20 pm

Admittedly, I agree – I don’t think one gallon’s worth is really going to make a difference. With that said, the fire engine really shouldn’t be leaking at all!