While going through an online course on EDX (Massive Open Online Courses) named Effective Thinking through Mathematics with Professor Michael Starbird, I came across couple of interesting puzzles. This course basically talks about how one can improve his thinking and make it very effective using mathematical reasoning in decision making. I am sharing those with you here in this post.
Puzzle 1: Gem in the Stone
Here are nine identical-looking stones. One can’t differentiate any one from the others. Eight of the stones weigh the same, but one of the stone containing the jewel weighs slightly more than the others
For your help you have got 2 balance scales. You may use each of the two balance scales exactly once. Is it possible for you to select the slightly heavier stone containing the gem (jewel) from among the nine identical-looking stones? Explain why or why not.