Total number of red balls = 6

Total number of white balls = 5

Total number of blue balls = 4

No. of ways of selecting 3 balls which is red = ⁶C₃

No. of ways of selecting 3 balls which is white = ⁵C₃

No. of ways of selecting 3 balls which is blue = ⁴C₃

Thus,by Multiplication principle, the total number of ways would be,

⁶C₃ ⁵C₃ ⁴C₃

Applying formula, ⁿC_r = , we get

⇒800 ways

Thus, the number of ways of selecting 9 balls from 6 red balls, 5 while balls and 4 blue balls if each selection consists of 3 balls of each colour would be 800.