There are 25 balls. 8 Green balls, 7 red balls and 10 white balls. How many minimum number of balls should I pick for getting red, green and white coloured balls?

There are 25 balls. 8 Green balls, 7 red balls and 10 white balls. How many minimum number of balls should I pick for getting red, green and white coloured balls?

In order to be sure of getting at least one of each colour, you must pick a minimum of 19 balls. Otherwise for 18 it's possible you picked the 10 white and 8 green.