Second, the tree diagram method is used to calculate the probability: the conditions for the tree diagram method to calculate the probability. When an experiment is designed with three or more factors, it is inconvenient to use the list method. In order to list all possible results without emphasis or omission, the tree diagram method is usually used to find the probability.
Probability is a numerical value to measure the possibility of accidental events.
If the experiment is repeated many times (denoted by X), the accidental event (denoted by A) appears many times (denoted by Y). Take X as the denominator and Y as the numerator to form a numerical value (denoted by P). In many experiments, P is relatively stable at a certain value, and P is called the probability of a certain occurrence. If the probability of accidental events is determined through long-term observation or a large number of repeated experiments, it is statistical probability or empirical probability.