There are 3 black hats and 2 white hats in a box. Three men (we will call them A, B, & C) each reach into the box and place one of the hats on his own head. They cannot see what color hat they have chosen.
The men are seated in such a way that A can see the hats on B & C's heads, B can only see the hat on C's head and C cannot see any hats. However, they can hear the responses of each other.
When A is asked if he knows the color of the hat he is wearing, he says no. When B is asked if he knows the color of the hat he is wearing he says no. When C is asked if he knows the color of the hat he is wearing he says yes and he is correct. What is the color of C's hat and how did C derive his answer?
Three subjects - A, B, and C - were shown seven stamps: two red ones, two yellow ones, and three green ones. They were then blindfolded, and a stamp was pasted on each of their foreheads; the remaining four stamps were placed in a drawer. When the blindfolds were removed, they could see the stamps on each other's forehead. A was asked, "Do you know one color that you definitely do not have?" A replied, "No". Then B was asked the same question and replied, "No".
Before C would be asked that question, C said, "Not only I know what color I do not have but I also know what color I do have." What color did C have and how did he derive that answer?