Black and white hats, version 3
A king had several advisors and he wanted to test them. He said that he had a
bag of white hats and a bag of black hats. The king seated the advisors facing
each other (around a round table) and blindfolded them. He told them that he would
pick hats from each bag (at least one from each bag), which would be placed on all
their heads so that they could each see the other advisors hats but not their own.
The king put the hats on their heads and removed their blindfolds. After staring at
each other for a while, the king told them to get up if they have a white hat on,
but got no response. The king asked again, but still no response, so the king
asked again, and this time got a response.