Center For Applied Teaching and Learning
to Yield Scientific Thinking

The Puzzle of Nine

Imagine that you have been given nine objects, identical in size, shape, and appearance. Eight of the objects have the same mass, while the ninth one has a slightly greater mass than the others. The difference in mass is so small that it can be detected only by using a balance. You have a double pan balance, but you may use it only two times. Your challenge is to design and describe a procedure to identify the object with greater mass.

Solution