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Logic Interview Question

Logic Interview Question - 9 August
black white balls

The first box has two white balls. The second box has two black balls. The third box has a white and a black ball.

Boxes are labeled but all labels are wrong!

You are allowed to open one box, pick one ball at random, see its color and put it back into the box, without seeing the color of the other ball.

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

For Solution : Click Here


  1. just one :
    get the ball from the box with label "white and black" -> if the ball is white then the box only contains white balls, "black" labelled box will have both black and white and "white" labelled box will have only black balls.

    Rest vice versa.

  2. Anand you are just awesome...nice answer

  3. 0, they told you in the beginning which boxes were which.

  4. 0, they told you in the beginning which boxes were which.

  5. There's only one required action. Fire the guy in the shipping department that packed and mislabeled the boxes. And drop this ridiculous "logic puzzle" from your list of interview questions, unless you're interviewing someone to work in shipping/receiving.

  6. Tks very much for your post.

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    Best rgs