The program of the New Year s Day party has 2 sketches, 1 street dance, 6 soloists, and 1 teacher ch

Obedient ... I guess there will be a queue at the door of the toilet.

Analysis:The 4 dance programs are not consecutive, and the interpolation method can be adopted. The other five programs have A55 kinds of arrangements, 5 programs have 6 air, and you can choose 4 from the 6 airs to arrange dance programs.

Answer:First arrange 2 cross talk and 3 solo singing, with a total of A55 methods; Insert 4 dance programs into the 6 empty spaces formed by the 5 programs above, and there are 64 ways to do this. According to the principle of step-by-step counting, all the permutations can be obtained, with a total of a55a64=43200 methods.

Comments:

This question mainly examines the practical application of the two basic principles of permutation and combination, and the key to solving this problem is to give priority to the restricted elements, and the "interpolation method" is generally used for non-adjacent problems, which belongs to the mid-range questions.

The remaining two after C (5,3) and A (3,3) will be repeated, such as a, bc, de and a, cb, de and a, cb, ed. So it's too much.

A watermelon went down with a knife and cut it into large pieces, small pieces, how did you cut it?

I have a headache when I see a math problem, and you say that you can't just finish it, which is so tangled.

How many percent more than 2 cross talk in 10 songs?

Answer: (10-2) 2=400%.

There were a total of 20 programs at the school's New Year's Day party, including sketches.

Songs, instrumental solos, dances and cross talk. There are 3 skits, 10 songs, and 1 instrumental solo. Among them, cross talk accounts for 50% of the dance. Q: What percentage of the total number of dances in the program?

20-10-3-1）x50%]÷20=20%

There are 4 singing programs in the first row, and there is the p(4,4)=24 method.

Secondly, 2 sketches and 4 dance programs will be arranged

1) Insert two vignettes between the 4 singing programs and 5 positions at both ends, with the method of p(5,2)=20, and insert 4 dance programs between the 6 programs that have been arranged and at the 7 positions at both ends, with p(7,4)=840

law, this class has 20 * 840 = 16800 law.

2) Two sketches are connected together, inserted between the 4 singing programs and one of the 5 positions at both ends, the two sketches can be transposed, there are 10 methods, 1 is drawn from the 4 dance programs and inserted between the two sketches, there are 4 methods, the sketch and its dance are regarded as 1 element, and the remaining 3 dances are inserted between the 4 singing programs (a total of 5 elements) and the 6 positions at both ends, there is p (6, 3) = 120 method, and this kind has 10 * 4 * 120 = 4800 method.

There are a total of 21,600 laws in the above two categories.

Therefore, the number of sorting methods is found = 24 * 21600 = 518400

1 (Dance accounts for all stanzas.)

What percent is the purpose? )

Answer: 4 20=

A: Dance makes up 20% of all programs.

2.(What percentage of all shows are crosstalk?) A.

Answer: 2 20=

A: Crosstalk accounts for 10% of all programs

1 (What percentage of the show is a skit?) )

Answer: 2 20=

A: Sketches make up 20% of all shows.

2.(What percent of the show is a song?) ）

Answer: 10 20=

A: Songs make up 5% of all shows.

Question (1) What percentage of the total number of dances is the number of dances?

A: The number of dances is 20% of the total number of programs

Question (2) What percentage of the total number of programs is the number of cross talks?

A: The number of cross talk is 10% of the total number of programs