As a test of intelligence, Mensa sits two candidates in closed room. The invigilator has three stickers, two white and one black. Upon each of their foreheads he places a sticker at random, so that neither candidate can see their own sticker. The candidate who identifies their own sticker first will be allowed entry into Mensa. After a few minutes, one of the candidates figured he had a white sticker. How?
He surmised that if he had a black sticker, then the other candidate would know they had a white sticker as there was only one black sticker. Therefore they must both be white.
© Kevin Stone: [www.brainbashers.com]
