Question

There are 3 marbles of the same size but one marble is slightly heavier or lighter than the other two. Can you find which is that marble and if it is heavier or lighter? You can use a balance only two times.

Answer 1

Let Ml, M2 and M3 be the three marbles. One of them is heavier or lighter than the others.

Put marbles Ml and M2 in different pans.

Case - I - If both will be equal, then M3 is heavier or lighter than these marbles.
Case - II - Put Ml and M3 in different pan,
(i) if they are equal then M2 is heavier or lighter.
(ii) Ml < M3, then M2 = M3 and Ml is lighter than Ml and M3.