A Guinness Book of Mind Benders riddle
from the book "Mind Benders" by
Robert Eastaway and David Wells.

Coloured Hats

Professor Pots has set a tough challenge for his four brightest students, who are seated facing each other.  He says "I have seven hats here, four are black and three are white.  I will blindfold you and then give you each a hat.  I will then remove the blindfold and ask each of you in turn, if you are able to work out what is the colour of your hat."

So, he does this.
Each student thinks very hard before he speaks.
And this is what each one says:
First Student:  "I don't know."
Second Student:  "I don't know either."
Third Student:  "Nor do I."
Before his blindfold was removed,
the fourth student announces the colour of his hat. 
What is it and how does he know?

Here is the fourth student's answer:
He says:"I am wearing a black hat."
His reasoning is as follows:
"Suppose my hat is white.  The first three students have already tried to work out the colour of their hats and failed. If number two could see white hats on number three and me, then he could deduce that his hat must be black (because if it was white, number one would have known his hat was black).  But number two said nothing, so if mine was white number three would know that his hat was black.  But since number three also said nothing, the only explanation is that I must be wearing a black hat."

Does she have something on her mind?  
                                     Only if she has her hat on!

Whenever I am down in the dumps, I buy A New Hat.                                         
Oh, So thats where you get them!

What did the hat rack say to the hat?
               "You go on a head!"          

Country Music comedienne, Minnie Pearl,
always wore a hat with a price tag on it.
What was the price on the tag?        
                                                                           $1.98