The answer process is:
1, first find the success probability of products A and B:
P(A)=40/50=0.8，P(B)=35/50=0.7。
2. The expectation of investing in product A is e (a) = 0.8 *100+0.2 * (80) = 64;
The expectation of investing in product B is E(B)= 0.7 * 80+0.3 *(50)= 4 1.
E(A) > English (b)
Therefore, it is better to invest in product A, because the average income level of A is higher than that of B.
Extended data:
The essence of mathematical expectation;
1, let x be a random variable and c be a constant, then E(CX)=CE(X).
2. If x and y are any two random variables, then E(X+Y)=E(X)+E(Y).
3. Let x and y be independent random variables, then E(XY)=E(X)E(Y).
4. let c be a constant, then e (c) = c
Expected application
1. In statistics, when you want to estimate the expected value of a variable, the method adopted is to measure the value of this variable repeatedly, and then use the average value of the obtained data as the estimation of the expected value of this variable.
2. In probability distribution, mathematical expectation and variance or standard deviation are important features of distribution.