A box contains three white balls, four black balls and three red balls. The number of ways in which three balls can be drawn from the box so that at least one of the balls is black is?
The required number of ways
(a) 1 black and 2 others = 4C1.6C2 = 4 × 15 = 60
(b) 2 black and 1 other = 4C2.6C1 = 6 × 6 = 36
(c) All the three black = 4C3 = 4
Total =60 + 36 + 4 = 100
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