Recitation 22 for any random variable, R. So Ex(R)=Ex R·I ∑Ex(R·IB) (linearity of Ex o) ∑Bx(R|E)Pr(E) by(1)Recitation 22 3 for any random variable, R. So � � � Ex (R) = Ex R · IEi (by (3)) � i = Ex (R · IEi ) (linearity of Ex ()) � i = i Ex (R | Ei) · Pr (Ei) (by (1))