SOLUTION: There are 3 red and 7 black marbles in a bag. If I am blindfolded, how many times must I reach in and pull out a marble before I am sure it is a black one?

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Question 138915: There are 3 red and 7 black marbles in a bag. If I am blindfolded, how many times must I reach in and pull out a marble before I am sure it is a black one?
Answer by edjones(8007)   (Show Source): You can put this solution on YOUR website!
4
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