Yeah, glad you figured it out.
I have 3 people, A, B, and C. They spend 6, 8 and 10 hours online a week, thus they average spending 8 hours a week online.
A spends 3 hours on Xbox, 3 hours on PS3, 0 hours on PC, 0 on Wii
B spends 6, 1, 0, 1
C spends 6, 1, 1, 2
The averages per system would be.....
xbox = 5, ps3 = 1.6, PC = 0.3, Wii = X
by your math, X would need to be HUUUUGE like 27, but in reality it is 1 in my example.
So, the statement of averages 8 hours online a week and the numbers make sense. Glad you figured it out though.