(Q). A box contains two white balls, three black balls and four red balls. In how many ways can three balls be drawn from the box if at least one black ball is to be included in the draw.
Solution:-
Since here in question it is not mentioned that ball are identical so we will assume all balls to be different.
Hence required number of ways = 1 black AND 2 other OR 2 blackAND 1 other OR 3black and 0 other
= ³C₁×⁶C₂ + ³C₂×⁶C₁ + ³C₃
= 45 + 18 + 1
= 64 Answer
