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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?

Note by Dina Andini Sri Hardina
4 years, 4 months ago

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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. · 4 years, 4 months ago

i don't know, i just write the original question. but thanks!:) · 4 years, 4 months ago

If the problem is on expectation, I get $$\dfrac{212}{49}$$ balls to be picked on average. · 4 years, 3 months ago

Sorry, my above answer is a blunder! I find the expectation to be $$\frac{8741}{2730}$$ · 4 years, 3 months ago

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. · 4 years, 4 months ago