Ethereum red yellow blue white 6

1. At least how many balls to touch is equal to at least how many balls to touch. That is to say, if you touch 5 balls of each color first, and then touch any one, you will get 6 balls of the same color. At this time, you touch a total of 5X4 + 1 balls. That is to say, if you touch at least 21 balls, there must be 6 balls of the same color
it was 22:30 when I saw the title, sorry.

2. There are six red, yellow, blue and white balls of the same size in the box. If you want to touch out one pair of balls, you must touch out at least five balls
red, yellow, blue and white four colors
if you want to touch out two pairs of balls, you must touch out at least seven balls
red, yellow, blue and white four colors, red, yellow, blue and white six balls each

3. There are six red, yellow, blue and white balls of the same size in the box. There must be a pair of balls of the same color that you want to touch. How many balls should you touch at least
there are four colors in red, yellow, blue and white. At least one pair of double colors. You have to touch at least five balls
two pairs of balls that you want to touch must be of the same color. Each color is six. The most extreme case is that after touching six of the same colors, there are three other colors. Only after touching one can you guarantee two pairs of double colors. That is, you need to touch 6 + 3 + 1 = 10. There must be two pairs of balls in the same color
of course, heavy color depends on how to understand it. If it's the same color, four are also two pairs of double colors. That's seven

4. There are six red, yellow, blue and white balls of the same size in the box. If you want to touch out one pair of balls, you must touch out at least five balls
red, yellow, blue and white four colors
if you want to touch out two pairs of balls, you must touch out at least seven balls
red, yellow, blue and white four colors, six balls each

good luck

5. It's so hard to calculate. Try using the method of plate separation, and you can't ask the teachers and students again. A33 * C36 * C23 * C11 / 3 ^ 6 = 40 / 81

6. There are 4 kinds, 2 kinds at random, 6 kinds in total

8. The worst case is that each ball has 5 balls of the same color. At this time, as long as you touch one more ball, no matter what color, there will be 6 balls of the same color.
a total of 4 balls × 5 + 1 = 21

9. The worst case is that each ball has 5 balls of the same color. At this time, as long as you touch one more ball, no matter what color, there will be 6 balls of the same color.
a total of 4 balls × 5 + 1 = 21