The Box with Ball

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There are three bags.The first bag has two blue rocks. The second bag has two red rocks. The third bag has a blue and a red rock. All bags are labeled but all labels are wrong.You are allowed to open one bag, pick one rock at random, see its color and put it back into the bag, without seeing the color of the other rock.

How many such operations are necessary to correctly label the bags ?

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  • 2 Answer(s)

    Just One!

    example
    If u get Blue rock with label as “blue+red” => this is red as all labels are wrong.
    In this way u can logically solve this puzzle.

    ronit Guru Answered on 8th August 2015.
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    This is a repeat of the ‘Orangaes & Apples’ problem. But the question is faulty.

    The question says: ” all labels are wrong“. A ‘wrong’ label on a bag NEED NOT necessarily match any other bag. (e.g. A label which says ‘black balls’ on a bag containing blue rock, another label that says ‘red flowers’ on the bag with red rock and a label ‘blue rocks’ on the bag containing blue and red rocks, are all ‘wrong‘, satisfying the condition mentioned in the puzzle. If this be the case, the only way you can correct the labels is by checking ALL bags.)

    Viji_Pinarayi Expert Answered on 4th December 2015.
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