Question:
How many different signals can be made from 4 red, 2 white and 3 green flags by arranging all of them vertically on a flagstaff?
Solution:
We have to arrange 9 flags, out of which 4 are of one kind (red), 2 are of another kind (white) and 3 are of the third kind (green).
$\therefore$ Total number of signals that can be generated with these flags $=\frac{9 !}{4 ! 2 ! 3 !}=1260$