Permutation and CombinationHard
Question
A box contains 2 white balls, 3 black balls & 4 red balls. In how many ways can three balls be drawn from the box if atleast one black ball is to be included in draw (the balls of the same colour are different).
Options
A.60
B.64
C.56
D.none
Solution
First we find 3 ball from 9 ball
9C3 = 84
Now number of ways if any one black ball not selected is 6C3 = 20
Here required no is 84 - 20 = 64
9C3 = 84
Now number of ways if any one black ball not selected is 6C3 = 20
Here required no is 84 - 20 = 64
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