There are three balls X, Y and Z. They are colored red, white and blue, but not necessarily in this order. One, but only one, of the following statements is true:
X is red
Y is not red
Z is not blue
How many solutions does the puzzle have?
The original question can be found in the Plus Magazine.
The picture shows George Boole (1815-1864), the author of the Boolean algebra. Boolean logic is credited with laying the foundations for the information age (computers and cell phones).