Three events of ABC occur at the same time as P(ABC), so none of the three events of ABC occur at the same time as 1-P(ABC).

Extended data:

Let the sample space of random experiment E be ω. If the real number P(A) is assigned to each event a of e according to some method, and the following axioms are satisfied:

(1) Nonnegativity: p (a) ≥ 0;

(2) Normality: p (ω) =1;

(3) Countable (complete) additivity: For an infinite number of countable events A 1, A2, ..., one, ..., which are mutually incompatible, there are

The real number P(A) is called the probability of event a.

The traditional probability is also called Laplace probability because its definition was put forward by the French mathematician Laplace. If a random test contains a finite number of unit events, and the probability of each unit event is equal, then this random test is called Laplace test. In Laplace test, the probability P(A) of event A in event space S is:

For example, in the random experiment of throwing coins and dice at the same time, assuming that event A is to obtain the national emblem and the number of points is greater than 4, the probability of event A should be calculated as follows:

S={ (national emblem, 1), (number, 1), (national emblem, 2), (number, 2), (national emblem, 3), (number, 3), (national emblem, 4), (number, 4). The probability of a is 2/ 12= 1/6. It is noted that there are some doubts about Laplace's experiment, and whether there is such an experiment in reality.

The probability of its unit event has exactly the same probability value, because people don't know whether coins and dice are "perfect", that is, whether the dice are made evenly, whether their center of gravity is in the center, whether the roulette wheel tends to a certain number, and so on. However, in practice, traditional probability is widely used to determine the probability value of events. Its theoretical basis is that if there is not enough evidence to prove that the probability of one event is greater than that of another, then the probability values of two events can be considered equal. ?

References:

Baidu encyclopedia-probability theory