In a box, there is a jumble of 7 red balls, 6 blue balls, 5 green balls, and 4 yellow balls. What is the minimum number of balls, will you have to pick up so that you have at least 4 balls of the same color?

We will have to consider the worst scenario which is 12 + 1 = 13.

You will have to pick up 13 balls to be absolute sure that you have at least 4 balls of same color