In a knockout tournament `2^n` equally skilled players, `S_1,S_2, S_(2n)` are participating. In each round, players are divided in pair at random and winner form each pair moves in the next round. If `S_2` reaches the semi-final, then the probability that `S_1` wins the tournament is 1/84. The value of `n` equals__________.

Answer

6

Explanation

Given `S_(2)` reaches the semifinals.
Since all other players `(2^(n)-1)` are equally likely to win the finals with proballity p. We have
`(2^(n)-1)+1/4=1`
`or (2^(n)-1)=3/4`
`or p=(3)/(4(2^(n)-1))`
If `p=1/84,then`
`1/84=(3)/(4(2^(n)-1))`
`or2^(n)-1=63`
`or 2^(n)=64`
`or n=6`