RI Permutation and Combination Tutorial Q1

\({9}\) coloured balls are arranged in a row. Find the number of ways this can be done if

1. all the balls are of different colours,
2. there are \({4}\) red balls, \({3}\) green balls and \({2}\) yellow balls,
3. there are \({4}\) red balls, \({3}\) green balls and \({2}\) yellow balls, and the arrangement is symmetrical.