Just in regards to the discussion and the issue of the aggregate. There was a lot of random trolling by many users yesterday, so here's the story:
What's true: The GAT is used at Monash for those in the Middle Band (and probably for other unis too, not sure) and having a good GAT does help you in you admission into certain courses that use it alongside you ATAR. No-on really knows what specific effect it has, but it has a beneficial effect if your GAT is fairly strong in the sections they are looking for.
What's false: The specific numbers: 9 or 6.5 or whatever else came up yesterday (I think a few users were involved, myself as well, and most of this was false/trolling). It DOES help Middle Band applicants(and there are technicalities as Russ pointed out above), but these numbers are all rumour. This is not the first time I've heard such numbers being thrown around (I even heard 12 at one stage last year lol, and other numbers in previous years), so if you did believe these to be true, just understand now that these numbers are probably not accurate. So, just know that is does help you if you are a middle band applicant with a good GAT.
Again, I'd like to apologise on behalf of all the tollers of yesterday for any misinformation