The secretary at a computers company is pregnant! It may have been one of the three partners' fault, or maybe someone else's. If a partner was the guilty party, he knows it... but he doesn't want the others to know it was him.

The three partners agree that they must know whether it was one of them who made the girl pregnant (thus possibly allowing a suit against the company) or if it was someone else.

How can they decide if one of them is to blame, without anybody having to accept being the father, if that was the case?

(Some notes: They might just write on papers either "I DID IT" or "I WASN'T IT", but the handwriting might give the guilty party away. Putting a white or black marble in an urn (white=innocent, black=guilty) might work, but someone could possibly see what color was being put in; also, if the guilty one went first, the second could peek inside and realize the answer. The optimum solution should not require much --or any-- extra equipment, and should "resist" inquisitive partners. And, of course, being all of them quite capable hackers, computers are out of the question!)

(In reply to re: Is there a method that doesn't involve whispering ? by TomM)

Isn't that the same kind of thing as the white/black marble, one of the other partners could potentially see if/how many balls were put into the urn?

How about this:

Everyone leaves the room except Bill. He places a pen in the center of the table, pointing in a particular direction, such as toward the window, etc (known only to him). He leaves the room, and each of the other partners enters, one at a time, and if they are guilty, they rotate the pen 90°. Afterward, they all reenter the room, and if the pen has moved (or if he himself is guilty), Bill announces that one of the partners is indeed responsible. If not, he tells the others accordingly.

Of course, if perhaps one could tell by listening if the pen was moved or not, then perhaps something slightly more complicated coud be devised; for instance, clockwise = innocent, counter-clockwise = guilty. If the pen is reversed, the other two partners are innocent, if it lies in its original orientation, one is guilty.

Posted by Aaron on 2004-02-23 11:27:47