In probability theory and statistics, mathematical expectation (mean) (or mean. Value (also referred to as expected value) is the probability that every possible result in the experiment is multiplied by the sum of its results, which reflects the average value of random variables.

Let the probability density function of continuous random variable x be f(x). If the integral is absolutely convergent, what is the value of the integral? ? Mathematical expectation of random variables, expressed as E(X):

What is the value of the discrete random variable x? Is the value corresponding to the probability of x, which can be understood as data? Frequency of occurrence, then:

Extended data:

nature

Let c be a constant and x and y be two random variables. The following are the important properties of mathematical expectations:

1.

2.？

3.

4. When X and Y are independent of each other, what are they?

Property 3 and property 4 can be extended to the sum or product of any finite number of independent random variables.

References:

Mathematical expectation-Baidu encyclopedia