
Ultimate access to all questions.
Three random variables X, Y, and Z have the equal variance of σ² = 2. X is independent of both Y and Z, and that Y and Z are correlated with a correlation coefficient of 0.8. What is the covariance between X and K given that K=Y+Z?
A
0
B
2
C
3
D
4
Explanation:
Recall from the properties of the covariance that:
So, we need:
This is true because X is independent of both Y and Z, which means:
The correlation between Y and Z (ρ = 0.8) and the variances (σ² = 2) are irrelevant for calculating Cov(X, K) since X is independent of both Y and Z.
Therefore, the covariance between X and K is 0.