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 Prime Perimeter (Posted on 2005-03-11)

You and two other people have numbers written on your foreheads. You are all told that the three numbers are primes and that they form the sides of a triangle with a prime perimeter. You see 5 and 7 on the other two heads and both of the other people agree that they cannot deduce the number on their own foreheads.

 See The Solution Submitted by Erik O. Rating: 2.8235 (17 votes)

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 re: centering the point | Comment 38 of 89 |
(In reply to centering the point by armando)

Armando,

1) it's tacitly said that the three numbers are primes.

2) it's tacitly said that the numbers could be sides of a triangle.

3) it's tacitly said that the perimeter is a prime.

4) it's tacitly said that the two others could not guess theirs numbers.

So, if my number could only be 3 or 5 or 7 or 11, and I eliminate the first three, it could only be 11. PERIOD!!

 Posted by pcbouhid on 2005-03-13 20:54:36

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