Who can give an answer to the math (liberal arts) in the college entrance examination paper? 15 is about the average unit yield of cotton A and B, which is relatively stable in five years. ...
Solution: The average value of A is (68+72+70+69+71)/5 = 70 ∴ The variance of A is 1/5 (4+4+0+ 1) = 2.
The average of b is (69+71+68+68+69)/5 = 69 ∴ The variance of b is1/5 (1+1+4+1) = 2.
The mean and variance of the two show that the average rate of return of A is higher and the rate of return is more stable.