For example, as can be seen from the figure below, there are 2 people in 52; 6 out of 57; 8 out of 62; 67 have 12 people; 8 out of 72; There are 6 people in 77 and 4 people in 82; 87 There are 3 people; In 1992, there were 1 person; There was 1 person in 1997.

Therefore, find the frequency of 52 = 2/(2+6+8+12+8+6+4+3+1).

Frequency of 82 = 4/(2+6+8+12+8+6+4+3+1+1).

Extended data

Nature of frequency

When the number of repeated experiments n increases gradually, the du frequency fn(A) shows stability and gradually stabilizes at a certain constant, which is the probability of event A. This "frequency stability" is also called statistical regularity.

Frequency has the following properties:

(1) Nonnegativity: 0 is less than or equal to fn(A) is less than or equal to1;

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

(3) additivity.