it doesnt matter about your raw school marks. the rank is all that matters. what they do is, they look at the cohorts hsc marks, then they look at the ranks and allocate occordingly to determine each persons school mark.
eg. Tom was ranked 1. hsc exam he got 90
Mel was ranked 2. hsc exam she got 92
Joe was ranked 3. hsc exam he got 84
each person keeps their own hsc mark. but for school assessment,
Tom will get 92. he gets the rank 1 hsc mark as his school assessment.
ie. Tom- School ass. 92. hsc exa, 90. total: 91
Mel 90 92 91
Joe 84 84 84