Car & Wheels — Puzzle for Interview rounds

Question :

A car has four tyres A, B, C and D and a spare tyre S. Each tyre can move a maximum distance of 20000 Kms.

What is the maximum distance the car can travel?

Assume that you can swap the tyres as and when required.

Solution :

Have you already solved it ? Congratulations !!

If not, let us be your guide.

The answer is 25000 Kms. Let’s see how…

• Let the car move on ABCD for the first 5000 Kms.
• Then swap A with S, and move 5000 kms.
• Then reinsert A and swap B with S.
• Similarly, swap C and D with S while reinserting the tyre taken out in previous process at 15000 and 20000 Kms.
• During the final journey, the tyre A B C and S will carry the car for 5000 Kms before finally wearing off.

So, the Car can travel 25000 kms like this.

Thanks for Reading

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