The expected value formula of hypergeometric distribution is Ex=nM/N, where x is the number of samples, n is the size of samples, m is the total number of samples, n is the total number of individuals in the population, and the variance formula of hypergeometric distribution is Vx=Xn_Pn-a_, where a is the expected value.

In probability theory and mathematical statistics, mathematical expectation is the probability that every possible result in an experiment is multiplied by the sum of its results, which is one of the most basic mathematical characteristics. It reflects the average value of random variables. It should be noted that expectations are not necessarily equal to common sense expectations, and expectations are 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.