1. Suppose lhat r of N chips are red. Divide the chips into three groups of sizes n a, n2 , and 113, w here n1 + 172 + n3 = N . Generalize the hypergeometric distribution IO find the probability tha t the firsl group contains ri red chips, the second group r2 red chips, and the third group r3 red chips, where r1 + r2 + 11 = r.
2. Some nomadic tribes, when faced with a life-t hreatening contagious disease. will try to improve their chances of survival by dispersing into smalle r groups. Suppose a t ribe of 21 people, of whom four are c.arriers of the disease, split into three groups of 7 each. What is the probability that at le,1st one i,011p is free of lhe Hint: Find t he probability of the complement.