There are 20 coins placed on a table such that tails is showing up. Suddenly electricity goes off and a boy sitting nearby inverts few coins and then he asks another boy to select some coins such that number of inverted coins is equal in every other subpart. He selects 8 coins and invert those 8 coins , and when electricity comes back he sees equal number of inverted coins in both subparts. Tell how many coins did first boy inverted.

P.S. The question is not original.

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## Comments

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TopNewestSounds like a potentially good puzzler. Although, what a

subpartis, isn't clear.Log in to reply

The problem is given in a technothlon problem . I am also confused with the term subparts. But it sounds like two groups from the phrase "equal number of inverted coins in both subparts". The options were given as 5 , 8 , 10 , 12. Now you can try.......

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What is a technothlon?

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Its answer is 8

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If you assume n coins to be inverted in both, then first would have inverted his n and others 8-n. So he inverted 8 in total

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Probably 10

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Read my answer. Its 8

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