1. A box contains 2 white balls, 3 black balls and 4 red balls. In how many ways can 3 balls be drawn from the box, if at least one black ball is to be included in the draw?
Ask Your Doubts Here
Comments
By: guest on 01 Jun 2017 05.47 pm
We may have(1 black and 2 non-black) or (2 black and 1 non-black) or (3 black). Required number of ways = (3C1 x 6C2) + (3C2 x 6C1) + (3C3) = 3 x 6 x 5 + 3 x 2 x 6 + 1 2 x 1 2 x 1 = (45 + 18 + 1) = 64.