Hiii...

For 38 marks, you may get within 2500.

The rank is based on the number of students qualified in GATE exam and their score. If many students get better marks than you, then your rank is high. Otherwise your rank will be low. It is not fixed .It depends on students performance, paper difficulty etc.

Every year So many people are applied to GATE. Some people may drop before writing exam . Most of the may not be qualified because it is one of difficult exam.

Hope you get it...