NO.PZ2021061603000034
问题如下：
Consider two variables, A and B. If variable A has a mean of-0.56, variable B has a mean of 0.23, and the covariance between the two variables is positive, the correlation between these two variables is:
选项：
A.negative. B.zero. C.positive.解释：
C is correct.
The correlation coefficient is positive because the covariance is positive. The fact that one or both variables have a negative mean does not affect the sign of the correlation coefficient.
根据公式 ：R=S/两个标准差的乘积， S是positive 那就是正号 ，标准差一正一负，然后相除以后得到CORRELATION,就是负的 所以是negative ,哪里理解错了？
