Q.5. Find the number of ways of selecting 9 balls from 6 red balls, 5 white balls and 5 blue balls if each selection consists of 3 balls of each colour.
There are 6 red balls, 5 white balls and 5 blue balls.
9 balls have to be selected in such a way that consists of 3 balls of each colour.
3 balls are selected from 6 red balls in .
3 balls are selected from 5 white balls in
3 balls are selected from 5 blue balls in .
Hence, by the multiplication principle, the number of ways of selecting 9 balls
.