if i get 3000 rank in open categoty in jee and if im a obc student which rank will i get as i have got reservation?

Though there is always different ranks provided for both the GE and OBC and other categories as well and according to your question it is very difficult to judge as to what rank you would get in OBC category even if you are getting 3000 rank in GE category but no doubt it would suely be within 500 to my guess.