e(X)= X 1 * p(X 1)+X2 * p(X2)+……+Xn * p(Xn)= X 1 * f 1(X 1)+X2 * F2(X2)+……+Xn * fn(Xn)

x； 1，X； 2，X； 3、……、X .

N is a discrete random variable, p(X 1)p(X2)p(X3), ... P (Xn) are the probability functions of these data, and p(X 1)p(X2)p(X3) is the random data.

App application

Because the demand (sales volume) x of this commodity is a random variable, which is evenly distributed in the interval, the profit value y of selling this commodity is also a random variable, which is a function of x and is called a function of random variables. The best profit involved in the problem can only be the mathematical expectation of profit (that is, the maximum of average profit). Therefore, the process of solving this problem is to determine the functional relationship between Y and X, then find the expected E(Y) of Y, and finally find the maximum point and maximum value of E(Y) by extreme value method.