... X2.6.5.25 Both parts of Exercise 6 .4. 1 hold true if the ch.f.’s involved are re-placed by m.g.f.’s, provided, of course, that these m.g.f.’s exist.ii) Use Exercise 6 .4. 1 for k = 2 and formulated ... xj∈ޒ, j = 1, . . . , k would be sufficient. (See Lemma 3 in Section 7 .4. )(ii) Definition 1 (as well as Definition 3 in Section 7 .4) also applies to m-dimensional r. vectors when ޒ (and B in Definition ... −()==∑∑μμμ2121222,whereXkXSkXXjjkjjk==−()==∑∑111212and .7.2.2 Refer to Exercise 4. 2.5 in Chapter 4 and find the E(X1X2), E(X1X2X3),σ2(X1+ X2),σ2(X1+ X2+ X3) without...