Hi Amulya!

The main thing behind the seat allocation is rank and not marks. This is because marks is the one which alters every year along with rank. Every year has it's own cutoff , high and low.

Depending on one's rank one is been allocated seats. To know furthur about it visit the JOSAA website regarding the same. Also since JEE MAINS has two filters, first the state quota and then All India Open. Both cannot take each other seats and number of seats are reserved for both .

Moreover, the seats are furthur divided according to the national reservation policy into General/SC/ST/OBC/PWD.

hope this answers your query,

cheers!