LOGIC/ RED HERRING QUESTION! HELP!!! (this is extra credit)?

Question

20 students were brought into a class room. the teacher made them stand in a circle and placed a black or white hat randomly on everyones head. the students could not see their own hat but could see everyone elses. they could not talk or they all would fail. they could not signal in any way. in a clockqise ritation, the students were told to say what color hat was on their head.

these students were smart though. they talked it over beforehand and figured out how to get everyone to pass and get their hat color right without depending on luck or chance. there were no reflective surfaces or windows in the classroom.

HOW DID THEY DO IT????

Answer 1

The man in front knew he was wearing a black hat because he knew the first man did not see two white hats and he knew that the second man did not see one white hat because if he saw a white hat, the second man would have known that his hat was black from hearing the first man's statement.