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.