Friends coming over to you for water puzzle


You have a large number of friends coming over and they all get thirsty. Your first friend asks for 1/2 a cup of water. Your second friend asks for 1/4 a cup of water. Your third friend asks for 1/8 a cup of water, etc.
How many cups of water do you need to serve your friends?friends-drinking-water-puzzle

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  • 3 Answer(s)

    1 Cup.

    Because 1/2+1/4+1/8+…….will add upto 1.This is a mathematical property

    dyj Expert Answered on 19th November 2016.

    That is incorrect. It is 7/8 of a cup. 1/2 (=4/8) + 1/4 (=2/8) + 1/8 = 7/8. It’s the law of common denominators.

    on 14th December 2016.

    It doesn’t stop after the third friend. It continues on with the “large number of friends”. Doesn’t matter exactly how many friends because eventually the series converges to 1. So 1 cup is correct

    on 14th December 2016.
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    3. You need a cup for each person.

    pmonster7 Starter Answered on 14th December 2016.
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    You need 7/8 of a cup.

    1st friend – 1/2 cup = 4/8
    2nd friend – 1/4 cup = 2/8
    3rd friend – 1/8 cup = 1/8

    4/8 + 2/8 + 1/8 = 7/8

    srgann Starter Answered on 14th December 2016.
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