A moderator takes a set of 8 stamps, 4 red and 4 green, known to three logicians, and affixes two to the forehead of each logician so that each logician can see all the other stamps except those two in the moderator's pocket and the two on his or her own head. He asks them in turn if they know the colors of their own stamps:
1. A: "No"
2. B: "No"
3. C: "No"
4. A: "No"
5. B: "Yes"

What are the colors of B's stamps?

 

B has 1 red and 1 green

A, B and C can all see eachothers stamps.  A has either 2 red or two green and C has 2 of the oposite color.  After neither of them can tell what color they have  you realize that B must have one of each color

Posted by Kristin on 2004-09-08 23:38:52