Questions 9 and 10 can be found in non-HSC/non-Australian online sources (although I cannot confirm an original source), which would make me doubt that they were written specifically for Mathematics Extension 2.
Question 11 can be found in AS and A-level mathematics sources. These are secondary school qualifications in the United Kingdom that are equivalent to the HSC. I found a version of this question with some minor differences in stimulus and question structure:
I hope this helps!