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:: Recommended ::
:: Collaborations ::
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:: Ball Problem ::
A bag contains a total of N balls with either blue or red colour. If five balls are randomly chosen from the bag, the probability is precisely 1/2 that all five balls are blue. What's the smallest value of N for which this is possible? (Hint: Use different number of blue/red balls to get to the answer?) Answer: 10. The question did not ask for number of blue/red balls, let's assume there are 9 blue balls and 1 red ball. The chance of randomly select 5 blue balls is (9/10) * (8/9) * (7/8) * (6/7) * (5/6) = 5/10
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