Are at least two people in the same Amanome (Zodiac) or only two people in the same Amanome (Zodiac)?

1。 If at least two people are the same

Then the opposite event is that the birthdays of six people are different from each other.

If one person's birthday is fixed, then the probability of the remaining five people is (x- 1)/x, (x-2)/x, (x-3)/x, (x-4)/x, (x-5)/x, which can actually be understood as the probability of the first person is x/x.

The probability of six different birthdays p1= (x-1) (x-2) (x-3) (x-4) (x-5)/x 5.

So the probability that at least two people are the same is equal to 1-p 1.

2。 Only two people are bound in the same way.

Six people, any two people with the same birthday, 6C2 combinations.

After binding, it becomes five people with different birthdays.

Referring to the above, P2 = (x-1) (x-2) (x-3) (x-4)/x-4.

So the probability that only two people are the same is 6C2*p2.

C is combination and p is arrangement. Haven't you learned this?

6C2 is the number of all possible species with 2 people randomly selected from 6 people.

For example, if you choose two numbers from the three numbers 1, 2, 3, there are three situations for a * * *: 12, 13, 23.

3C2=3