I failed all my internal hsc assessments except maybe 1 or 2. But i really want to make it to uni. Is it possible for me to get an atar of at least 75?
You'll only know if you can get that desired ATAR if you stop asking "if it's possible" and just study very hard for your externals instead because there's nothing else that can be done about your internals now.
Also, your school rank and your rank in each subject will also determine whether it's possible. But all you can do now is study for externals.
What do you mean by fail? A fail can be anything. It can be someone aiming for 99.95 and only got 99.90 and said that they 'failed the hsc'. Or it can be someone aiming in the 90s but only got in the 80s and failed. Or it can be your miserable below 50% fail.
a friend of my last year had a internal mark for business of 29 he end up getting a band 3. Even if you fail your hsc its not end of the world, u just have to admit the fact you fuk'd around a lot. theres many ways of getting into uni
all i can say is head up and look for other options