There are 6 white, 5 yellow and 13 green balls in the urn. Determine what is the minimum number of balls you need

There are 6 white, 5 yellow and 13 green balls in the urn. Determine what is the minimum number of balls you need to simultaneously extract at random from the urn so that among them there are: a) two green balls b) two white balls c) two yellow balls d) two balls of different colors

1. To get two green balls for sure, you need to collect all yellow and white balls plus two green balls:

6 + 5 + 2 = 13 b;

2. To be sure to get two white balls, you need to collect all yellow and green balls plus two white balls:

5 + 13 + 2 = 20 b;

3. To be sure to get two yellow balls, you need to collect all the white and green balls plus two yellow balls:

6 + 13 + 2 = 21 b;

4. To get two balls of different colors, you need to take all balls of the least amount of color and one more:

5 + 1 = 6 b.

Answer: 13 balls; 20 balls; 21 balls; 6 balls.