Suppose that two random variables X and Y have a joint density function given by f(x,y) and by checking we find that f(x,y) does not equal f(x)f(y). That is the two are not independent. Some of the calculated moments are E(X)= 10, E(Y)=8, V(X) = 9, V(Y) = 4, E(XY) = 84.
1) What is the expectation of the random variable W = X+Y+4
2) What is the variance of the random variable W?
3) What is the correlation coefficient of X and Y?