You need 8 balls of one color

For maximum balls it has to be (n-1) of all but one colors and n of last colors.

Like:
We need 8 same colored balls
it may happen that i selected 7 balls and all are of same color
i slected next and its of diffrent color
and next 7 makes another color
so at end I may end up with

7 White
7 Red
7 Blue and
7 Green

and any 1 more ball will make 8 balls of 1 color
so in worst case we need 28 + 1 = 29 balls.





n = 8
and colors = 4

(8-1) * (4-1) + 8
=29

Hope this helps!!

Man, are you seeking the worse scenario, because the the question asks you to [b]make sure[/b]? Otherwise you'll go on with the usual calculation?

is it that the reason?

thanks
Andrew[/b]