RRB Group D Notice on Score and Response Sheet & FAQ on Normalisation of Marks (CEN 02/2018) 

Railway Recruitment Boards
Ministry of Railways
FAQ on Normalization of Marks
Q. Why examination is conducted in multiple sessions?
A. RRB examinations attract exceptionally large number of candidates. In order to take examination 
for such a large number of candidates, examination has to be split in various sessions keeping in view 
the limitations of the capacity of examination venues available across the country. For example, CEN 
02.2018 for Level 1 post had attracted 1.89 Crore candidates and the examination was conducted in 
153 sessions.
Q. Why normalization is necessary?
A. When an examination is conducted in multiple sessions for the same syllabus, in spite of all efforts...

All dtaila with marks : cilick here