11.2.6. Let Y1 and Y2 be statistics that have a trinomial distribution with parameters n, 1, and 2. Here 1 and 2 are observed values of the random variables 1 and 2, which have a Dirichlet distribution with known parameters 1, 2, and 3; see expression (3.3.10). Show that the conditional distribution of 1 and 2 is Dirichlet and determine the conditional means E(1|y1, y2) and E(2|y1, y2)