After blindfolding them, Paul picks up the five red discs, sticks one on the forehead of each logician, and hides the other discs elsewhere. After removing the blindfolds, everyone sees the discs (all red) on the others' foreheads but not the one on his own.

After a few minutes, one of the logicians (that reasons a little faster than the others) correctly states the color of his disc. How does he work it out?

Tanx, the original that I submitted stated that all five, at the same time, figure out itīs color disc. When the problem was being voted, this change was made because some of the "voting people" (JM), questioned about "same speed of reasoning", that was in the original.

Posted by pcbouhid on 2005-10-15 14:11:32