four pages work

Consider the following joint distribution of X and Y. For example, P(X=-200, Y=-100) = .3, P(X=-200, Y=100) = .1, etc.

XY	-100	100
-200	0.3	0.1
200	0.2	0.4

 a) Calculate the mean and variance of X

 b) Calculate the mean and variance of Y.

c) Calculate the covariance and correlation between X and Y. Is there a positive or negative relationship between X and Y? Is the relationship strong, weak or moderate?