Hotel room ab

Five people live in three rooms,

Suppose it is 1, 1, 3, and there are 5X4=20 species; If it is 2,2, 1, there are c (2,5) X3=30 kinds, that is, * * * has 50 possibilities.

There are six kinds of A and B that meet the first situation, because only three people can live in a room, while another person has three possibilities, and the other two rooms can be exchanged, multiplied by two, which is six possibilities; If A and B satisfy the second condition, there are 20 kinds of C (5,2)+C (5,2).

To sum up, the probability is 13/25.

Probability, also known as probability, probability, probability (probability) or possibility, is the basic concept of probability theory. Probability is a measure of the probability of random events. Generally, the real number between 0 and 1 indicates the probability of events. The closer to 1, the more likely it is to happen. The closer to zero, the less likely it is to happen. If someone is sure to pass the exam, what is the possibility of something happening? These are examples of probability.