4. Prove that the intersection and difference of two measurable sets are measurable. [Hint: For two sets E₁ and E2, we can write (EE) EU E and E1-E2-E1ПE.] 5. Prove that the symmetric difference of two measurable sets is measurable. [Hint: The symmetric difference of two sets E₁ and E2 is given by E14E2-(E1-E2) U(E2-E1); apply the result in Problem 4.]