RRB NTPC CBT-1 cut-offs are declared after the exam and differ for every RRB region, post group and category.
CBT-1 is only a screening test — its marks do not count in the final merit, but you must clear the zone-wise cut-off to reach CBT-2.
The cut-off depends on vacancies, applicants and paper difficulty, so it changes every cycle.
Check the official cut-off PDF on your regional RRB website for your zone and category.