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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(3): full solution as understood | Comment 25 of 89 |
(In reply to re(2): full solution as understood by Charlie)

I agree with Charlie  on scenario 1.

but scenario 2. is not possible because if C were seeing 3 and 7 then 3 is not a possibility for C. As sum of two sides of a triangle is greater than third side.

so scenario 1. is still possible.

Lets check scnario 3. may be it is not possible and our number is 5 not 11.

What do you think Charlie and pcbouhid ?

Edited on March 12, 2005, 4:12 am

Edited on March 12, 2005, 4:12 am
 Posted by Sachin on 2005-03-12 04:11:29

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