Your internal mark in a particular subject contributes 50% of the overall HSC mark for that subject. It is calculated using two elements:
- Your rank relative to your cohort (which is determined through your performance in your internal assessment tasks/exams)
- The performance of your cohort (including yours) in the HSC exam of that subject, i.e. the external marks achieved by all students in your cohort.
This process is called moderation. Essentially, the higher your internal rank in a subject, the higher your internal mark (the technical name for which being the Assessment Mark) can be. Based on this, suppose a student receives an external mark of 85, and that mark is the third highest in the cohort. If you are ranked third internally, you will receive a mark similar to 85 as your internal mark.
The external mark (the technical name for which is the Examination Mark) contributes the remaining 50% of the overall HSC mark for that subject. The way that your external mark is calculated is more straightforward since it depends solely on your own performance in the HSC exam of the subject. It is therefore unaffected by factors such as your rank relative to your cohort or your school rank. While it is subject to a process called alignment, this has no effect on your ATAR.
In terms of your question, the answer depends on the rank of your school, as this provides an indication of the academic capability of your cohort. Such ranks at a high-ranked school typically lead to favourable internal marks, whereas they may lead to lower internal marks at a lower-ranked school. However, since your goal is a 70+ ATAR (which tends to be the average ATAR), you will likely be able to achieve it. A 70+ ATAR typically requires band 4's across your subjects which, from your post, seem definitely possible. Of course, the better you can perform in your HSC exams, the higher your chances of reaching your desired ATAR.
I hope this helps!
