Find the fake coin
Computer Science
Level
2
There are 8 coins of Rs 10. One of them is a fake coin. The weight of the fake coin is less than the genuine. A two-pan balance scale is given without weights. Find the minimum number of tries to identify the fake coin.
The answer is 2.
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1 solution
Step 1 - Weigh any 3 + 3 coins on each scale.
Case 1 - If there is weight difference, the fake coin lies among those 3 which is on the lighter side.
Case 2 - If there is no weight difference, the fake coin lies among the remaining 2 coins.
Step 2 - Weigh any 2 coins among the suspected group of coins
Case 1 - If there is weight difference, the fake coin is the one that is lighter.
Case 2 - If there is no weight difference, the unweighed coin is the fake coin.