Since every player will have their own loot in cooperative play, the Magic Find in group situations will be averaged across the group.[3]

Here's an example with a group of three people:

Player 1's MF: 100
Player 2's MF: 80
Player 3's MF: 0
Magic Find for each player: (100 + 80 + 0) / 3 = 60.
To recap: Every players personal Magic Find will be summarized and then divided by the number of players.

This prevents players in public games from stacking Magic Find and tagging along while doing minimal effort in killing monsters but getting the best chances of getting great drops. This might also discourage cooperative play since other people with low Magic