Using the table A3, I figured that if I got into the 50th percentile, just the 50th percentile for all my subjects - I would already get an ATAR around 92.50. Just by that.
My working, scores are for P50:
Chemistry - 33/50
English (Adv) - 32.1/50
English (Ext 1) - 37.4/50
English (Ext 2) - 37/50
Legal Studies - 26.2/50
Maths (Ext 1) - 42.1/50
Maths (Ext 2) - 46/50
Physics - 31.8/50
With those, my counted subjects would be Maths (Ext 2) with 92/100, Maths (Ext 1) with 84.2/100, English (Ext 1) with 37.4/50, English (Ext 2) - 37/50, Chemistry with 66/100, English (Adv) with 64.2/100 - meaning Physics with Legal Studies not counting.
Adding the aggregate, I get 380.8/500, which from using Table 8b, a 90 ATAR's minimum aggregate was 367.4, with 95 ATAR is 401.5, meaning it's an ATAR of around 92.50.
That surely cannot be right - unless P50 is extremely difficult to get, and I don't think it is. My question, is my working correct? If so, this HSC thing is easier than I thought =P