4 people from 6 people will be selected to visit A, B, C, and D scenic spots

1.There are 55 ways to go to A.

2.A does not go to a There are c41*c41*a44 methods.

Add up to 504

Answer D analysis: This question is a step-by-step counting problem, first arrange the tour method of city A, A and B can not participate in the tour method of the city bureau of A city has 4 ways to choose, and then look at the remaining three, you can choose any of the remaining five people, and get the result according to the principle of step-by-step counting

Answer: There are 4 ways to visit city A, 5 ways to visit city B, 4 ways to visit city C, and 3 ways to visit city D

According to the principle of step-by-step counting, there are 4 5 4 3 = 240 different options, so choose d Comments: This question examines the step-by-step counting problem, and when solving the problem, you must distinguish how many steps you need to do it, each step contains several methods, see the idea clearly, and multiply the numbers in several steps to get the result, which belongs to the mid-range question reference.

Categorical summing:

1. A and B don't go, there is a total of p(4,4)=4!= 24 schemes 2, A goes to B and does not go, a total of 3xp (4, 3) = 3x24 = 72 schemes 3, B goes to A and does not go, as above, there are 72 schemes.

4. A and B both go, a total of p(3,2) x p(4,2)=6x12=72 schemes.

Therefore, there are a total of 24 + 72 + 72 + 72 = 240 schemes.

Answer: Step by step, special elements, special location questions, special elements, special positions are given priority In this question, there are fewer positions and more elements, you should start with the location, it is easier to arrange d first, then there are 4 options.

There is no restriction on other positions, it is a matter of arrangement, there are a(5,3)=5*4*3=60 kinds, a total of 4*60=240 different browsing schemes.

If there is no A and B among the 4 people selected, there are a total of a(4,4)=24 kindsIf there are 4 people selected A and no B, there are a total of 3*c(4,3)*a(3,3)=72 kinds, and there is B without A, the same.

If 4 people are selected from A and B, there are a total of a(3,2)*c(4,2)*a(2,2)=72 species.

In total, there are 168 schemes.

Solution: A and B don't go to A, so there are 4 people who can go to A. Choose one of these 4 people to go to A, and there are 5 people left in the wild.

3 out of 5 people are selected to go to BCD, and there are A(5,3) methods.

There are a total of 4*a(5,3)=240 possibilities.

There are 4 ways to arrange a city A first, and then there are 5 ways to visit city B, and then there are 4 ways to visit city C, and then there are 3 ways to visit city D According to the principle of step-by-step counting, there are 4 5 4 3 = 240 different options, so choose D

Solution: A does not go to city A, but goes to other cities, there are 3 options;

B does not go to city A and does not go to city A, there are 2 options;

Two of the other 4 people want to go to the other two cities separately (A and B did not go), and there are 8 3 11 choices;

The last 2 people can go to all four cities, i.e. 4 4 8 options.

The options are: 3 2 11 8 24 (pcs) There are 24 possibilities.

。If you don't understand, you can ask.

A goes to BCD City.

B goes to BCD City.

A and B together are three situations, 4 people to three cities is to choose three people to three cities n=3*2*1=6

Then choose one person to go to one of the four cities n=6*4=24A and B are not together, and 4 people choose 2 people to go to 2 cities n=(C4 2)*2=24

There are also two people who go to four cities, they can be together, or they may not be togethern=24*4+24*4*3=384

Total n = 384 + 24 = 408

There are 840 answers to the exhaustive list of computer programs.

There are 4 chances of choosing the Yu Ant who went to Paris first, and then there are 5 people left. There are 5 options to go to B, and then there are 4 people left. There are 4 options for going to C, and there are 3 options for going to Void D. 4*5*4*3=240