How are these numbers calculated?

Big Games

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

Week of 4/15100.0*Chance in playoffs100.0*Average seed
North Gwinnett 0 Mill Creek High 1 In
+0.5
Mountain View H 0 Habersham Centr 4 -0.9
Duluth High Sch 2 Meadowcreek Hig 0 +0.5
-0.1
Mill Creek High 2 Peachtree Ridge 0 +0.2
Week of 4/18None
Points
Chance Will Make Playoffs