Its not like the companies are losing revenue, because its the schools that purchase the practise exams, not the students themselves.
This is a good point. You can't just go "pirated copies" multiplied by "price" and say: that's how much revenue they're losing! You have to analyse the demand curve, and have a look whether people would have actually bought it for that price.
I don't think many individuals are buying practice exams. Mostly it's just schools that buy them (they are bloody expensive!) and just because they're online, doesn't mean schools are going to stop purchasing!
Exactly. The whole point is that people access the exams that their school HASN'T supplied. There's no point downloading an exam that your teacher has already given out. In no way is this going to decrease the amount of exams purchased by schools. (generalisation, but correct enough for this argument)