Hey as per my idea For admission to IIM's Institute , the ST category needs to bring percentile 75-85 ( cut-off) . Yes , the seats at least 10-15% is reserved for SC/ST/OBC category .

Qualification
Candidate should be graduate from recognised university
Final year candidate can also apply

Here I am giving you list of IIM fees
INSTITUTE NO.OF SEATS FESS STRUCTURE (2013-2015)
IIM (A) 385 16,60,000
IIM (B) 382 15 LAC
IIM (C) 462 13,50,000
IIM LUCKNOW 419 12,50,000
IIM INDORE 450 13 LAC
IIM SHILONG 120 8 LAC
IIM (K) 360 9,75,000
IIM (RAIPUR) 120 9 LAC
IIM UDAIPUR 120 9 LAC
IIM TRICHY 102 10 LAC
IIM ROHTAK 120 9 LAC
IIM RANCHI 120 9 LAC
IIM KASHIPUR 42 8 LAC

Selection criteria
Written test
Group discussion
Work experience
Academic past records
Essay writing
Interview