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blue Eyes

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#1 Aaron Burr

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Posted 29 June 2007 - 05:48 PM

Perhaps you've heard this one before, it's the best example i've heard of an inductive reasoning puzzle.

There are 200 hundred inhabits on an island. 100 of them have blue eyes, the other 100 do not (their eye color is irrelevant). These numbers are not known to the inhabitants, and for the moment they do no know their own eye color. On this island there are 3 rules that all the inhabits must follow.
1. No one may know his/her’s own eye color
2. If some one figures out their own eye color they must leave the island
3. When they leave it must be at midnight of the day they discovered it

Now a strangers comes to the island and the 200 gather before him. He calls out “I see someone with blue eyes” Then he leaves.

The puzzle is: How many people leave the island and on what day?
(And all the inhabitants are completely logical, there are no mirrors and the answer is also completely logical i.e. nothing cheep and it's not a lateral thinking puzzle)

Spoiler for Solution

- He's not dead... he's electroencephalographically challenged
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#2 rookie1ja


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Posted 29 June 2007 - 06:20 PM

nice one ... I have published a variation on that a while ago - check puzzle called Josephine
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