There are 20 red, yellow and blue balls of the same size and texture in the pocket. Only when you touch at least a few balls at a time can you guarantee at least four colors The same color? Process and answer

There are 20 red, yellow and blue balls of the same size and texture in the pocket. Only when you touch at least a few balls at a time can you guarantee at least four colors The same color? Process and answer

3 × 3 + 1 = 10
Answer at least 10 at a time to ensure that at least 4 colors are the same