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?

Algebra ->  Probability-and-statistics -> 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?      Log On