Bro it varies every year and that too institute to institute.i took this exam 3 years ago and had got AIR 9 (obc rank 3) but what i could remember now is that u will have to attempt atleast 70 to 80 prcnt of paper and with accuracy more than 90 prcnt to be in top 20.NDRI had only 3 seats and closed before rank 10,similar is the situation for other colleges too.so dont get any thing pre assumed or predicted for the exam.attempt whole paper,rather for targeting no of questions and no of marks.questions are not tough,just it checks your fundamentals and formulae....
All the best