Weighted averages are not usually officially taught in K-12, which is a little odd, because student grading is usually done using weighted averages. The following problem is easily solved using weighte averages.

A league has 11 teams. Eleven is used to simplify things since each team plays against 10 others. Each pair of teams plays the same number of games as every other pair. One team wins every game and the other 10 teams have an equal number wins and llosses against every other one of the 10 teams.

The one team has winning record of 100%. What is the winning percentage of the other teams?