12.21.2010

The Dancing Beans

In a pot, there are 75 white beans and 150 black beans. By the pot, there's a bag of black beans. A playful chef takes out the beans from the pot one by one like this: he randomly picks two beans- if at least one is black, he puts it in the black beans bag and the other one (regardless of its colour) back into the pot. If both beans he picked are white, he throws them away and puts a black bean from the bag into the pot.
Each time he does that, the pot holds fewer beans, and in the end only one bean is left in the pot. What is its colour?

4 comments:

  1. Nice one!! Logic thinking is enough!

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  2. At the end the bean who is left in the pot is white, because white beans get out from the pot only in pairs and they are 75. So, being the white beans odd, the bean who is left in the pot is white.

    ROCCO from Italy

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  3. Yes, Rocco, you are right! :)Good thinking!

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