SSC CGL (Prelims) General: Permutations and Combinations questions with solutions

Q1. In a tournament of 9 players, each plays every other player once. How many matches are played?

1. 72
2. 40
3. 42
4. 36

Answer: 36

In a round-robin tournament, each match is formed by choosing 2 players out of 9. The number of matches is ${}^9C_2 = \frac{9\times 8}{2} = 36$.