Question

you have 8 marbles, 7 of which are the same weight 1 isn't. how do you figure out the lightest marble if you can only weight them twice using scale with two balances.

Answer 1

Firstly we will divide all 8 marbles into 2 sections. Each section contains 4 marbles.

Then we balance each section and find that one section is lighter than other.

Then we take lighter section and further divide it into 2 sections and each section contains 2 marbles.

Then we balance them again and we find the lighter section further divide it into 2 sections and each section contains 1 marble, balance them and we get the lightest marble.