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The great tunnel switch II (Posted on 2008-12-26) Difficulty: 3 of 5
There are 4 doors to the secret Truth Club room, each one at the end of a tunnel leading there. Each of the members has a keycard to a different door. All the doors are unlocked from the inside, but to enter from the outside, one needs to swipe the door's keycard to open the door for a few seconds.

You have found a copy of one of these cards, and want to prove beyond a reasonable doubt to the club members that you can unlock one of the doors, however, you don't want to expose to anyone whose door it is. What can you do to show this? (preferably with no additional materials, and without anybody else inside the cave/tunnels)

(Assume the club members are honorable enough to follow their part of the plan you propose.)

Here is a map of the tunnels:

A map of the tunnels

No Solution Yet Submitted by Gamer    
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What's In the Cave? | Comment 1 of 9
While not probably what Gamer is seeking, as this does not seem to in the same vein as one he recently presented, I'm offering this for consideration and/or debate.

If I am to prove within a reasonable doubt that I can unlock one of the doors (and at that point none of the members need know that I have a keycard) I think it sufficient to suggest that all four doors are one-way secured, ie, I can open any from the inside and walk out.

While that might be construed a good guess on my behalf I can merely suggest furnishings and adornments (or lack of) within the sanctum.

If further proof is need the exposure of the card should substantiate all of the above claims.

  Posted by brianjn on 2008-12-26 21:14:42
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