Question

In a tennis tournament, each of six players plays withevery other player exactly once. How many matches are played during the tournament?

• A. $12$
• B. $30$
• C. $36$
• D. $15$

Answer 1

The correct option is D $15$

There are 6 players, lets call them A, B, C, D, E and F.
A plays 5 matches with B, C, D, E and F.
B plays 5 matches with A, C, D, E and F. Match with A has been accounted for in A's matches, i.e, 4 matches.
So, total matches$=5+4+3+2+1=15$