riddle the ants crossing a bridge
We’re going to solve a very curious mathematical riddle. Maths are so much fun, and so helpful!


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Hello Happy friends!
Are you ready to learn?

I’m Sarah, and today, we’re going to solve a very curious mathematical riddle.
But don’t think it’s going to be about adding, subtracting, multiplying or dividing.
No, no, maths isn’t just that!
We also use maths to develop our creativity, and solve problems that we come across every day.

I’m going to show you a little riddle called the ants crossing crossing a bridge, and we’re going to see how to solve it!

It’s nighttime, and four ants are being followed by a hungry anteater.
Suddenly, they come up to an old narrow bridge!
One of them, has a light on its head so they’re able to see, and she realises, that the bridge is so old, only two ants can cross at a time, so they will only be able to cross individually, or in pairs.
And they always need the light, because otherwise, they can’t see!

The anteater will take 17 minutes to get to where the ants are, to eat them all! What can our ant friends do to save themselves?

Let’s see, you’re the slowest, and you’re going to take 10 minutes to cross the bridge.
You’re going to take 5, you’ll take 2, and because I’m the fastest, I will take 1 minute.
And we only have one light!
And the anteater is going to take 17 minutes to get here, what shall we do?

These little ants need our help, let’s get our thinking caps on!
But if you need a little more time, pause the video.

Have you figured it out?
Let’s take a look!

If two ants go together, they will take the same time as the slowest ant.
So the best idea is that and 1 and 2 go together.
They’ve spent 2 minutes crossing.

Now, ant 1 will cross back with the light, and she will take another minute.
That means, in total they’ve taken 3 minutes.
Who should cross the bridge now?

Ant 1, will give the lamp to ant 5, and this one crosses the bridge with ant 10.
If we add these 10 minutes, to the 3 we had before, we’ve taken 13 minutes.

Now, the ant that goes back with the lamp is ant number 2, who takes 2 minutes.
So they’ve taken a total of 15 minutes, and the anteater is about to arrive!

So, the ants we’ve got left are the ones that take 1 and 2 minutes.
How long will they take?

Of course! it’s two minutes!
And if we add them to the 15 minutes we had before, we’ve reached a total of 17 minutes!

Yes! we’ve saved our little ants! And it’s all thanks to our maths!

The truth is, maths are so much fun, and so helpful!

Goodbye happy friends! See you next time!

I hope you’re always ready to learn!


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