AAPL wrote:Veritas Prep
There are 16 teams in a soccer league, and each team plays each of the others once. Given that each game is played by two teams, how many total games will be played?
A. 256
B. 230
C. 196
D. 169
E. 120
Since there are 16 teams and each team plays every other team once, the number of games played is 16C2 =16!/[2!(16-2)!] = (16 x 15)/2! = 8 x 15 = 120 games.
Alternate Solution:
Let's see the pattern that develops:
The first team plays each of the 15 teams besides itself..
The second team has already been paired with the first team, so it plays each of the remaining 14 teams.
The third team has already been paired with the first two teams, so it plays each of the remaining 13 teams.
Each of the remaining teams follows a similar pattern, so we see that the total number of pairings is the sum: 15 + 14 + 13 + ... + 3 + 2 + 1. This is an evenly-spaced set, with an average of (15 + 1) / 2 = 8, and there are 15 terms in this set. Thus, the number of pairings is 8 x 15 = 120.
Answer: E
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