Probability:

2. '2n' players S₁, S₂.........S_2n play in a tournament. They are divided into n pairs at random. From each pair a winner is decided onthe
basis of a game played between the two players of the pair. Assume that all the
players are of equal strength
(a) find the probability that the player S₁ is among the eight winner
(b) find the probability that exactly one of the two players S₁ and S₂ is among the 'n' winner.
(c) It is found that S₄ is among the 'n' winners and S₁ is not among this 'n' winners. Find the probability that S₁ and S₄were
in the same pair.

for the first ques is the answer ^r-1C₂ 9w^r-3(w+3)^r-1 ..

Please post the solution.

No utd4ever, ans given is 3(r-1)(r-2)/[(W+3)(W+2)(W+1)]

noone?