问题如下:
The variances of Stock A and Stock B are 0.25 and 0.64 respectively, and the correlation between two securities is 0.09. What is the covariance of returns?
选项:
A. 0.036.
B. 0.0144.
C. 0.048.
解释:
A is correct. Cov(RA,RB)=ρ*σA*σB=0.09*0.250.5*0.640.5=0.036
为什么不写开根号,而要写0.5次方,虽然意思都一样。但是我觉得开更号表达的关系更一目了然些,0.5次方,还要转个弯。