A bag contains 6 red balls, 5 green balls and 4 yellow balls. How many balls must you take out to be sure that you have at least 3 balls of each color?

I literally have no idea for this question. Should I just put 15(take all of them out to be sure?) or is there some kind on formula that I'm missing out on. THANKS!! You don't have to do it for me, but if there's a formula or something maybe tell me the name of it? Thanks everyone, Samantha.

1 answer

You might take all 6 red balls, all 5 green balls first. So, you might have to take out 6+5+3=14 balls to be sure you also have 3 yellows.

Extra credit: how many do you need to be sure you have 3 balls of some color? Hint: There are 3 colors.