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Interview Brain Teasers Medium 3 min

You have 8 identical-looking balls and one is heavier. What is the minimum number of balance-scale weighings needed to guarantee finding it?

Hint
Split the balls into groups of 3, 3 and 2.

Answer

2 weighings.

Explanation

Weigh 3 against 3. If balanced, the heavy ball is among the remaining 2. Otherwise it is in the heavier group of 3. A second weighing identifies it.

Step-by-Step Solution

First weighing: 3 vs 3.
Second weighing identifies the heavy ball within the remaining group.
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