A somewhat tricky, but not overly difficult problem of logic:

Three people take a total of five hats, two blue and three red into a bag. They then pick, at random, a hat from the bag, and without looking at it, put it on. (So they can each see each other's hat, but not their own.) Next, in order, they each try to logically determine what color hat they are wearing, and state (honestly) whether or not they know the color.

Well, it so happens that on this particular round, they all choose red hats. The first person, says, "I do not know what color my hat is." The second person then says, "I also do not know what color my hat is." Finally the third person says, "My hat is red." How did the third person know what colour his hat was? Answer