Frequency, a mathematical term, refers to the ratio of the number of times each object appears to the total number of times, and the ratio m/n is called the frequency of events.

Under the same conditions, n experiments were carried out. In these n experiments, the frequency m of event A is called the frequency of event A. ..

The ratio of the frequency of a population to the sample size is also called the frequency of this population. With frequency (or frequency), we can know the distribution of numbers.

Frequency has the following properties:

(1) Nonnegativity: 0 is less than or equal to fn(A) is less than or equal to 1.

(2) Normality: fn (ω) = 1 (Note: ω stands for sample space).

(3) additivity.