So far I've had 2 SACs for PE, in which I scored 39/40 (40% of unit 3) and 60/60 (20% of unit 3). Say if I drop maybe 3 marks per semester and go into the exam with rank 1...
If I choke in the exam and do not get the highest mark, what happens? Will it drastically affect my score? Please explain in situations such as scoring an A+, A, or B+; or if I rank as low as 10 - 15 in the exam (roughly 95 students enrolled in PE at my school).
Thanks.
The marks you've been getting for your SACs is largely irrelevant out of context. Your ranking is important, combined with how good you are objectively (not always measured accurately by yours SACs - easy teacher, hard teacher, etc).
Half your study score is YOUR exam score. So you have to do well to have a really high study score.
The other half of your study score is: the exam score from your school that has the same ranking as your SAC ranking. If you're highest in SACs, you get given the highest exam score for your SAC mark. If you're second in SACs, you get the second-highest exam score for your SAC mark. If you're last in SACs, you get the lowest exam score for your SAC mark.
As McFries said, the marks your teacher gave you all on your SACs are entirely irrelevant: it's the ranking.
To see how well you need to do on the exam to be on track for a particular study score, check the VCE stats on the VCAA page (they change slightly each year, but not too much). For example, in Legal you need about 90% for an A+, and if you get an A+ on both SACs and exam you start to break into the 40s. ***Not 90% from your teacher - 90% AFTER they do that score-matching exercise described above***
In other words, beat everyone else in your school in SACs, and then make sure ALL of you kill it in the exam (as in, share notes and help the weaker people prepare, too) because you are likely to be getting someone else's exam score counting for half your study score. Forget the exact mark your teacher gives you.
In response to your concern about choking: if you choke in the exam, you've brought down half your study score. You're then relying on someone else to kill the exam so you can get a high "moderated" score for your SACs. If no-one else kills the exam, you get a low mark for your SACs as well.
Short answer: do your best; work together; worry about today and not the future. How well you do today is in your control; how well the whole school and state do in November is not.