Hello guys, how are you?
Say we have to find Var(((a-1)/a) x) which equals with ((a-1)^2/a^2) Var (x)
But if we try Var(((a-1)/a) x)= Var((1-(1/a))x) =Var(x)+(1/(a^2))Var (x)
= (1+1/(a^2)) Var (x) is a different result from ((a-1)^2/a^2) Var (x).
With an arithmetic example we see that the first way is correct but what is really going wrong with the second way? Thank you very much!