# Identify the Counterfeit Coin: 3 Weighings Only!

• ruko
In summary, the "3 Weighings Only" method is a logical approach for identifying a counterfeit coin among a set of 12 coins. It involves weighing the coins in groups of three and comparing the weights to determine which group contains the counterfeit coin. This method can only be used for 12 coins and the coins should all have the same weight except for one counterfeit coin. The scale used for weighing should also be accurate and precise. However, with additional information about the counterfeit coin, this method can be used for sets of 13, 14, or 15 coins. While it may not always be the most efficient method, it is a reliable approach that can be used in many situations.
ruko
12 Coins. One of the coins is counterfeit. The counterfeit coin is either heavier or lighter than the good ones. You have a simple balance. With just 3 trips (three weighings) to the balance isolate the counterfeit coin and tell if it is heavier or lighter. No extra weights for the balance.

Sorry, previously submitted and answered. i should have done a search.

## 1. How does the "3 Weighings Only" method work in identifying the counterfeit coin?

The "3 Weighings Only" method is based on the logic that if we have a set of coins, and we weigh them in groups of three, the counterfeit coin will either be lighter or heavier than the other coins. By comparing the weights of each group, we can determine which group contains the counterfeit coin.

## 2. Can this method be used for any number of coins?

No, this method can only be used for a set of 12 coins. If there are more than 12 coins, it will not work as we need to have 3 groups of 3 coins and one individual coin for the third weighing.

## 3. Are there any other conditions or restrictions for this method to work?

Yes, there are a few conditions that need to be met for this method to work. The coins should all have the same weight except for one counterfeit coin. Also, the scale used for weighing should be accurate and precise.

## 4. What is the maximum number of coins that can be identified using this method?

This method can identify the counterfeit coin in a set of 12 coins. However, if we have additional information about the counterfeit coin, such as whether it is heavier or lighter than the other coins, we can use this method to identify the counterfeit coin in a set of 13, 14, or 15 coins.

## 5. Is this the most efficient method for identifying a counterfeit coin?

It depends on the number of coins and the available information. In some cases, this method may not be the most efficient, but it is a reliable and logical approach that can be used in many situations where a counterfeit coin needs to be identified.

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