[OK]

See Details
Privacy Policy + T&C

We use cookies to personalise content and adverts. We also share information about your use of our site with our advertising partners who may combine it with other information you’ve provided to them or they’ve collected from your use of their services. You also agree to our terms and conditions (T&C).

BB Logo
Spacer
Line
Line

Difficulty: MediumPuzzle Details:

You have a pile of 24 coins. Twenty-three of these coins have the same weight, and one is heavier.

Your task is to determine which coin is heavier and do so in the minimum number of weighings.

You are given a beam balance (scale), which will compare the weight of any two sets of coins out of the total set of 24 coins.

How many weighings are required to identify the heavier coin?

Show Hint Show Answer Print Puzzle
[Ref: ZYUQ]  

Answer: It can be done in three weighings.

Weighing 1: Break the coins into three piles of eight. Weigh one group of eight against another group of eight. If the scale balances, then the group that hasn't been weighed has the heavier coin. If the scale tips, then that group contains the heavier coin.

Weighing 2: Break the group of eight that has the heavier coin into three groups (three coins, three coins, and two coins). Weigh one set of three against the other set of three. If it balances, the group of two has the heavier coin. If the scale tips, then that group has the heavier coin.

Weighing 3: If the heavier coin is in the group of two, then just weigh one coin against the other to determine the heaviest coin. If the heavier coin is in a group of three, then take two of those coins and weigh them against each other. If the scale balances, the coin that hasn't been weighed is the heavier coin. If the scale tips, then that is the heavier coin.



Our Favourite Illusions

 Shadow Illusion

 What Am I?

 Hidden Faces

 Impossible Waterfall?

 Same Eyes?

 Impossible Prongs?

 Duck Or Rabbit?

 Spinning Dancer

 Who Turned To?

 Blind Spot

 The Butterfly

 Parallel Cafe Wall Lines?

 

 



BrainBashers™ is a trademark. We use cookies to personalise content and adverts. We also share information about your use of our site with our advertising partners who may combine it with other information you’ve provided to them or they’ve collected from your use of their services. For more information please view our privacy policy. By using the site you also agree to our terms and conditions.

Line
Line