There are 8 balls. All of them have the same weight, except one that is lighter. How can you identify the lighter one in 3 steps, using a balance?

+5 votes

There are 8 balls. All of them have the same weight, except one that is lighter. How can you identify the lighter one in 3 steps, using a balance?

+2 votes

Best answer

It can be done in two steps ONLY !!

make two groups of 3 balls each and one group of 2 balls (i.e 3+3+2=8)

Step 1: Measure group of 3,3 on the weighing machine.

case 1. If two groups are equal then the defected(less weight) ball is in group of 2 balls.

Step 2: Measure those two balls, you will get the defected one. [2 steps only]

case 2. If one of the group of 3 balls is less heavy then that particular group contains the defected ball. divide this group into 3 groups of 1 ball each (i.e 1+1+1=3).

Step 2: weight any two balls ...If one of those two is less heavy then that is your answer.if both are equal then the third ball is answer. [2 steps only]

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