Saturday, July 24, 2010

Brain Teaser

Solve this: A room has two doors. Behind one is a million dollars; behind the other is a fire-breathing dragon. Two guys are in the room one of whom always tells the truth while the other always lies. They both know what lies behind the doors, and they both know about how the other guy either always lies or always tells the truth. You have only one opportunity to ask only one of the guys one question that will indicate to you which door to open to get at the million dollars. What question do you ask, and of whom?

5 comments:

Arie denHollander said...

Ask the guy who tells the truth: "What door would your amigo say the money is behind?"

Then choose the opposite door.

George van Popta said...

Oops, I forgot to add that you don't know which is the liar and which the truth-teller. But, no matter: ask either guy what the other guy would say, and choose the opposite.

Arie denHollander said...

I assumed that we didn't know! Thanks for challenging my and my kid's brains this morning!

Have a good Sunday tomorrow. May God bless you on the pulpit (assuming that's where you will be and that you are not on holidays!)

Arie

George van Popta said...

Thanks, Arie. I am in my own pulpit tomorrow. And may God bless you at the organ console, if that's where you will be, and in the pew.

Mrs. Bob said...

walk up to each door and bang on it. the one that releases the puff of smoke is the one hiding the fire breathing dragon. the other will have the million dollars.