If you have a solid understanding of how the system works then you would realise that all school's mark differently and have different assessments. There is no way you can make an assumption of whether someone will achieve a specific UAI based only on their half yearly marks, therefore this assumption below is incorrect.
It's important to note that:
1. All school's mark differently and have different assessments with different levels of difficulty, therefore you can't make an assumption based purely on marks. You can't compare an 80 at one school with an 80 at another.
2. Half yearly marks, only make up a small part of your end hsc mark.
3. If you don't get the mark you want in your half yearly it doesn't mean that the UAI you are aiming for is not achievable. It just means you need to work harder, re-evaluate your studying strategies etc in order to work out how you can achieve the mark you are aiming for.
lilsxcwog89: Nothing is impossible, if you try your best, work harder, re-evaluate your studying strategies etc you can work towards achieving the UAI you want.