Open the website of the regional RRB you applied through and look for the Group D cut off or result notice.
The cut off PDF lists zone-wise and category-wise cut off marks for UR, OBC, SC, ST and EWS candidates.
Compare your normalised score against the cut off for your zone and category.
Cut offs are released separately for CBT, PET and the final merit stages.
Only trust the cut off published on the official RRB website.