If in a box there are 3 blue balls, 4 red balls, 7 yellow balls and 2 green balls, then how many times we have to take a ball at random so that we would get 2 balls of the same color?

I think your question needs editing, it should rather be "how many minimum no. of balls one needs to pick to assure that he gets atleast 2 balls of the same colour". Then the answer would be 5 using PHP.

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TopNewestI think your question needs editing, it should rather be "how many minimum no. of balls one needs to pick to assure that he gets atleast 2 balls of the same colour". Then the answer would be 5 using PHP.

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i don't know, i just write the original question. but thanks!:)

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If the problem is on expectation, I get \(\dfrac{212}{49}\) balls to be picked on average.

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Sorry, my above answer is a blunder! I find the expectation to be \(\frac{8741}{2730}\)

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5 . Because if we need 4 chances to pick a ball of every colour then another chance will surely be the second ball of any colour.

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Thanks:D

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