The chances are based on the previous year cut-off data. These chances give a student a fair idea of the possible colleges that he might get admission based on his/her rank or score.

Thank You

The predictions are based on official data. You could check. Most of it is available while some have to be asked from the institutes. For CCMT alone for NIT admissions, there is the question of spot round and stuff. All the others generally give one cutoff. So it is presumed that these institutes like IITs are giving the base cutoff on which admissions are given. I also think that it is good to know that the cutoffs are there to give an idea else students would be pretty clueless.