Assuming the balls to be identical except for difference in colours

Probability

Assuming the balls to be identical except for difference in colours, the number of ways in which one or more balls can be selected from 10 white, 9 green and 7 black balls is

  1. 880
  2. 879
  3. 629
  4. 630

Answer

Number of ways of selecting one or more balls from 10 white, 9 green, and 7 black balls

= (10 + 1)(9 + 1)(7 + 1) – 1

= 11 × 10 × 8 – 1

= 879

The correct option is B.