Expectation is not necessarily equal to "expectation" in common sense-expectation is not necessarily equal to every result. The expected value is the average of the output values of variables. The expected value is not necessarily contained in the set of output values of variables.
The law of large numbers stipulates that as the number of repetitions approaches infinity, the arithmetic average of numerical values almost inevitably converges to the expected value.
Extended data:
Let the number of times of random event A in N repeated tests be nA, and if the frequency nA/n swings around a certain value P stably when the number of tests N is large, and the amplitude of its swing becomes smaller and smaller with the increase of the number of tests N, then the number of times P is called the probability of random event A, and it is recorded as p (a) = p
If a random variable only takes a finite number of values or can be listed in a certain order, its range of values is one or several finite or infinite intervals, such a random variable is called a discrete random variable.
The probability of an event is a measure of the possibility of an event. Although the occurrence of an event in random trials is accidental, those random trials that can be repeated in large numbers under the same conditions often show obvious quantitative laws.
Baidu Encyclopedia-Mathematical Expectation