All about flooble | fun stuff | Get a free chatterbox | Free JavaScript | Avatars    
perplexus dot info

Home > Logic
12 on foreheads (Posted on 2008-12-17) Difficulty: 3 of 5
Two players, A and B, both have the number 12 written on their foreheads.

Each one sees the number on the forehead of the other one, but does not know his own number.

A third person, C, tells them that the sum of their two numbers is either 24 or 27 and that it concerns only two positive integer numbers greater than zero.

Then C asks again and again alternating A and B whether they can determine the number on their foreheads.

A: No.
B: No.
A: No.
B: No.
A: No.

After how many “no"s, can one figure out his own number? Or there is no way, after all?

See The Solution Submitted by pcbouhid    
Rating: 4.0000 (1 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
Hints/Tips The Undiscovered Numbers (spoiler) | Comment 1 of 2
This is a specific case of Hugo's problem from several years ago,
<a href="show.php?pid=4051">The Undiscovered Numbers</a>

It looks a little different, because you know the other person's number and not yours, but it is really the same problem.


  Posted by Steve Herman on 2008-12-17 12:44:05
Please log in:
Login:
Password:
Remember me:
Sign up! | Forgot password


Search:
Search body:
Forums (0)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (14)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Chatterbox:
Copyright © 2002 - 2024 by Animus Pactum Consulting. All rights reserved. Privacy Information