a)Does any one know what to do to the variance when multiplied by a number? I know that when added together:

$ Z = X + Y => Var(Z) = Var(X + Y) $

I seem to remember something like:

$ Z = aX => Var(Z) = a^2Var(X) $

This may be completely wrong... Any ideas?

b)Since the equation for the correlation coefficient is

$ p(x,y) = \frac{cov(X,Y)}{\sqrt{var(X)}\sqrt{var(Y)}} $