hi ashok, the population of backward classes in tamilnadu is 46.14%.the percentage of seats reserved for them is 30%.the non reserved category s population in tamilnadyu is 12.95%.the percentage of open competition seats is 31%. if the upper castes get lesser marks than the backward castes in the open competition,who is to be blamed? see this webpage. http://www.tamilnation.org/caste/reservations.htm
