50% of your HSC mark (final mark) in a particular subject is contributed by the Assessment Mark, and the remaining 50% is contributed by your Examination Mark. The Assessment Mark is subject to the moderation process and the Examination Mark is subject to alignment. The moderation process uses Examination Marks to adjust the Assessment Marks. You don't solely receive a band 6 based on your performance in the HSC exam of a particular subject. Keep in mind that the Assessment Mark contributes 50% of your HSC mark, meaning that it can therefore affect the possibilities of a band 6. An important factor to consider with respect to the Assessment Mark is your rank relative to your cohort. The higher it is, the better the Assessment Mark that you can expect. To illustrate that a particular band is not determined solely based on the Examination Mark, suppose that a student did not perform well in their school-based assessment tasks/exams, leading to an unfavourable rank and an unfavourable Assessment Mark. However, they managed to figure out a more effective study strategy and rectified a number of mistakes as they approached the HSC exam, leading them to a favourable Examination Mark. In the event where the Assessment Mark and Examination Mark happened to be 70 and 90 respectively, the HSC mark will
, placing the student in the band 5 zone for this particular subject.
Regarding your Mathematics Extension 2 question, and considering the example that was given above, I believe a band E4 would be possible. A factor that this will depend on is the performance of whoever achieves the second-highest Examination Mark, as this is the mark that will be used to moderate (adjust) your Assessment Mark.
I hope this helps!