Depends on the selection process of that school:
e.g. The report is more important in schools that DON'T set entrance exams... A good example of this is Sefton...
Here's some estimates of weightings (they are just VERY ROUGH ESTIMATES)
Schools that set entrance exams (e.g. Fort Street, Sydney Tech, Hurlstone, James Ruse, North Sydney Boys, North Sydney Girls, etc.)
Entrance Exams - 50%
Half Yearly + Yearly Report - 40%
Extra Cirriculars + Sporting Achievements - 10%
But yes, as LoveHateSchool said, different schools will treat extra cirriculars differently....
You may ask why extra-cirriculars only weigh around 10% to 20%, this is because we all know that selective schools want academically strong students in the end....
If a guy got all As and another guy got all Bs but has heaps of extra cirriculars, I'd dare say that the guy with all As will still have more preference....
Schools that don't set entrance exams: (E.g. Baulko (Apparently?), Sefton, etc.)
70% Half Yearly and Yearly Reports
30% Extra Cirriculars and Sporting Achievements
Also, what school are you trying out for? This information can allow us to help you even further.