Can you solve this famous logical puzzle about people with green eyes?

3 min


Imagine there’s an island where a mad dictator holds 100 people captive, and every one of them is great mathematicians. They can’t escape, but there’s one strange rule governing their captivity. At night, any prisoner is allowed to ask the guard for his freedom. If he has green eyes, he’ll be released, otherwise, he’ll be dropped into a volcano.

It seems that each one of 100 prisoners have green eyes. But they’ve all been living on the island since they were born, and therefore the dictator has done all that he can to make sure that none of them will ever be ready to determine what color eyes they need. There are not any mirrors on the island, and every one water visible to the prisoners is opaque – thus, they can’t see their reflection. And most significantly, the prisoners aren’t allowed to speak among themselves.

Nevertheless, they see one another at utterance every morning. Everybody knows that nobody will dare invite their freedom unless they’re absolutely sure of their success. Under considerable pressure from human rights organizations, the dictator was forced to allow you to go to the island and speak to the prisoners, but only under the subsequent conditions. you’ll only make one statement, and you can’t provide them with any new information. So how are you able to help the prisoners without breaking the agreement with the dictator?

After much thought, you tell the crowd: ‘At least one among you has green eyes’. The dictator is extremely suspicious, but he’s sure your statement won’t change anything. You leave, and therefore the life on the island seems to continue along its usual course. But one morning, 100 days after you visited, the island suddenly becomes empty – the previous night, all the prisoners asked to go away. So how did you manage to outsmart the dictator?

So, what is the answer?

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