A Mensa Problem

"caryle clear" (cpcj@sprynet.com)
Sat, 25 Oct 1997 21:49:16 -0400


| 
| You are in a room with two doors.  There are two men, one each guarding a
| door. One door leads to certain destruction.  The other door leads to
| freedom. One man is a liar, never telling the truth.  The other man
always
| tell the truth.
| 
| What ONE question can you ask each man and find out which way to safety.
The
| same question is asked to both men.
| 
| Sis Wendy Horn

Ok, I'll give it a shot.  Let's just say, for the sake of clarity that
there is man A (with door A) and man B (with door B).

You ask man A first..."Would person B say that door A leads to freedom?"
"A" says yes, person B would say "yes", door A leads to freedom.

You ask man B..."Would person B (himself) say that door A leads to
freedom?"
"B" says "yes", which means person A was telling the truth, and therefore,
B is lying, ergo...Door A does NOT lead to freedom.

**If B says "no".  Then person A was lying, B is telling the truth, 
ergo, door A still doesn't lead to freedom.

For this scenario, door B leads to freedom.

NOW...
If A says "no", person B would NOT say door A leads to freedom.  
If B says "no", then A was telling the truth and B was lying,
ergo, door A does indeed lead to freedom.

If B says "yes", then A was lying, and door A still leads to freedom.

For *this* scenario, door A leads to freedom.

Since you ask each question only once, following this pattern, you would
still come to a correct answer regardless of what A said first.
Is that close?
Anneliese