Can you please explain why did we add = 5+4+3+2+1 here?
We need to find the total number of points that can be gained by all teams together. For this, we need the total number of matches played since each match can give either (3 + 0) points to the two teams or (1 + 1) points to the two teams.
We say there are 6 teams - A, B, C, D, E and F
A plays a match with all 5 so 5 matches have been played.
Then B plays a match with C, D, E and F so another 4 matches were played (note that B has already played with A above).
Then C played with D, E and F so another 3 matches were played.
Like this, we get that the total number of matches played = 5 + 4 + 3 + 2 + 1 = 15
The 15 matches could have contributed a maximum of 3*15 = 45 points and a minimum of 2*15 = 30 points (since each match would have a winner-loser or it would be a draw).
Required difference = 45 - 30 = 15
Veritas Prep | GMAT Instructor
Get started with Veritas Prep GMAT On Demand for $199
Veritas Prep Reviews