Probability :Knock Out Tournament Of Ranked Players 
Thirty-two players ranked 1 to 32 are playing in a knockout
  tournament. Assume that in every match between any two players, the
  better-ranked player wins, the probability that ranked 1 and ranked 2
  players are winner and runner up respectively, is ?

I dont understand. Should'nt the player ranked 1 always be the winner as the better ranked guy always wins?

The top ranked player will always win, but the second ranked player will only reach the finals if he doesn't play the top ranked player in the first 4 games. In a knockout tournament with a bracket that means that they must be on opposite halves of the bracket, but in a tournament without a set bracket you are looking for the probability that the player ranked second doesn't play the player ranked first in each round.
$R_{1} * R_{2} * R_{3} * R_{4}$, where $R_{n}$ is the probability of surviving each round, or:
$\frac{30\text{ wins}}{31\text{ possible opponents}} * \frac{14}{15} * \frac{6}{7} * \frac{2}{3} = 0.516129$
