Let (X1,...,Xk) be Multinomial with parameters n and (p1,...,pk). Use indicator r.v.s to
Chapter 7, Problem 64(choose chapter or problem)
Let (X1,...,Xk) be Multinomial with parameters n and (p1,...,pk). Use indicator r.v.s to show that Cov(Xi, Xj ) = npipj for i 6= j
Unfortunately, we don't have that question answered yet. But you can get it answered in just 5 hours by Logging in or Becoming a subscriber.
Becoming a subscriber
Or look for another answer