E(X)=∑kp 1∑k(k-1+∑kq] k=1 =1 =qp(∑q")"+E(X)=91q1 =1 9 p 2q12 qp g p 2 2 Ppp Var(X)=E(X)-E(X) P P 2 2 P PVar(X)=E(X2 )-[E(X)]2   = − = 1 2 2 1 ( ) k k E X k pq [ ( 1) ] 1 1 1 1    = −  = − = − + k k k k p k k q kq   = =  1 ( ) k k qp q +E(X) q p q qp 1 ) 1 (  + − = q p qp 1 (1 ) 2 3 + − = p p 2q 1 2 = + 2 2 p − p = 2 2 p − p = 2 1 p − 2 1 p − p =