In a box, there are 20 balls of red, yellow, blue, green and white. At least touch a few balls to ensure that there are two balls of each color? Come on the sooner the better Within an hour

In a box, there are 20 balls of red, yellow, blue, green and white. At least touch a few balls to ensure that there are two balls of each color? Come on the sooner the better Within an hour

20 * 4 + 2 = 82
The reason, with the worst idea, if you touch all the "red, yellow, blue and green" in front of you, that is, you touch 20 * 4, but there are still no white balls! Then you have to touch two more!

There are four red, yellow and blue balls of the same shape and size in the box. If you close your eyes and feel out four balls at will, at least two balls will have the same color
Why?

Because [4 divided by 3] + 1 = 2
So at least two balls will be the same color
Note: integer value of quotient in mathematics

There are seven red, yellow and blue balls of the same size in one pocket. At least () balls should be found at a time. Two balls must be of the same color

At least (15) small balls should be touched at a time, and two of them must have the same color
Your adoption is the driving force for me to move forward, and it can also bring you wealth value

There are red, yellow, blue, green four different colors of the ball, put them in three boxes, no matter how to put, at least one box has______ A small ball

4÷3=1… 1 (piece), 1 + 1 = 2 (piece); answer: there are at least two balls in one box

18 apples are divided into 3 points on average. How much is each apple?

6

Mother asked Tutu to divide the 19 apples into three parts according to 1 / 2, 1 / 4 and 1 / 5 of the total number?

The comprehensive formula is: 19 + 1 = 20 (pieces) 20x1 / 2 = 10 (pieces) 20x1 / 4 = 5 (pieces) 20x1 / 5 = 4 (pieces) 10 + 4 + 5 = 19 (pieces)

Divide 7 apples to 5 children on average. The second child gets () apples, and the second child gets () apples

The average of 7 apples was divided into 5 children, the second child was divided into (1 / 5) apples, and the second child was divided into (1.4) apples
I'm a teacher. Thank you

If you give 30 apples to 7 children, and each of them gets at least one, and the number of apples they get is different from each other, there are different grading methods

Thinking process: imagine 30 apples in a row, and there are 29 holes between them. Let seven children in a row, holding baskets numbered 1-7 in their hands. Our task is to divide 30 apples into seven groups, and put them into the seven baskets, and the number of each group can't be 0

Give 30 apples to 7 children, each of whom will get at least one, and each of them will get different numbers. How many ways can they get?
The answer is to use the board method C (29,6). I personally think it's not right. The method of C (29,6) includes the same number of points,

Since each person has at least one, then they are divided into seven children according to one, two and seven. At this time, 28 children have been distributed. If the final distribution result is sequence xn = {x1, X2, X3, x4, X5, X6, X7}, if xn lacks one of 1-7, such as X, then the minimum sum of XN is (1 + 2 + 3 + 4 + 5 + 6 + 7 - x)

Divide the 15 apples into 5 portions, each of which is 5 / 1, accounting for 3% of these apples

Five thirds