How are these numbers calculated?

Big Games

How we did last week and who we should root for this week.   Explain

Week of 6/8100.0*Chance wins title100.0*Average seed
USA 9 Tonga 18 No
-0.6
Canada 36 Tonga 27 -3.0
Week of 6/19100.0*Chance wins title100.0*Average seed
Fiji 35 USA 10 -0.5
Japan 16 Canada 13 -0.1
Week of 6/23100.0*Chance wins title100.0*Average seed
Japan 38 USA 20 -0.4
Games Above .500
Chance Will Win Championship