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You are blindfolded and placed in front a table with two jars. One jar has $50$ red balls and other has $50$ blue balls.

What should be your strategy so that you pick up the red ball with more than $50\%$ probability.

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    Sin$c$e the rules seem to be incompletely defined (nothing is said about what you can and cannot do after being placed in front of the table, as @celtschk notes), my strategy would be to remove the blindfold!2012-08-17

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Take one ball from each jar. You're guaranteed to get a red.

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    There is no strategy that you can use to guarantee more than 1/2 are red.2012-08-17
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If the red and blue balls are identical in shape and size and picking one ball from two jars which are also identical should result in the probability of getting a red ball as .5. Now if the experiment is biased in some way, then the probability of getting a red ball may be greatr than .5.

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I don't think moving the balls makes any difference.

The question is what is your strategy to improve from 50% of the balls. Not 50% out of one jar.

Ultimately there are always 100 balls in front of you and you have a 50/50 chance. The only way to change that is to take two balls out, or throw away one balls so that N changes.

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take 49 red balls from one jar and put them in the other jar wit the blue balls,

now its 100 % he will pick red from the first jar, and 50% red from the mixed jar.

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    But you don’t know which jar has the red balls, so you can’t perform the desired rearrangement of the balls.2013-05-16