Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!watmath!clyde!burl!ulysses!bellcore!decvax!linus!philabs!cmcl2!harvard!seismo!umcp-cs!aplcen!osiris!ken
From: ken@osiris.UUCP (Ken Harkness)
Newsgroups: net.puzzle
Subject: Re: another puzzle
Message-ID: <677@osiris.UUCP>
Date: Thu, 13-Feb-86 15:42:37 EST
Article-I.D.: osiris.677
Posted: Thu Feb 13 15:42:37 1986
Date-Received: Sun, 16-Feb-86 05:14:36 EST
References: <1645@hound.UUCP>
Organization: Johns Hopkins Hospital
Lines: 27

> 
> 
>      Three men are in a room. The room has no mirrors and the three men
> are in a straight line such that the person in the back of the line
> can see the two people in front of him, the middle person can see
> only the person in front of him, and the person in front can't see
> anyone. Another person walks in with a bag containing 3 black hats
> and two red hats. The man pulls three hats at random out of the bag
> and places them randomly on the three men. He walks out of the room.
> The man in the back says,"I don't know what color hat I'm wearing."
> The man in the middle says,"I don't know what color hat I'm wearing, either."
> Now tell me what color hat the man in the front of the line is wearing
> and why.
> 
> 
>                                                 Barry Friedman
>                                                 ihnp4!houxm!hound!5125kaf

Black.
If #1 and #2 had red hats on, #3 would know that he had a black one,
so either #1 and #2 have both black hats or one they have 1 of each color.
However, if #1's hat is red, then #2 knows he must have a black hat on,
since he knows that it cannot be red (from sentence 1).  Therefore,
#1's hat is black.

ken harkness
seismo!umcp-cs!aplcen!osiris!ken