Hey Leela! There is no proper marks scoring which a candidate cnana get <=5000 rank, this changes according to the performance of candidates and difficulty of paper. But scoring 220+ marks ensures rank <5000. You need to work hard for that. You can also apply for careers360 scholarship exam to get scholarship and to check your preparation. 

https://learn.careers360.com/careers360-talent-search-exam/

You have to score about 125-150 to get a rank of 5000 in her mains to get a secured position. But to get into NIT try to score around 200 where your rank will be around 1K. You will have high chance to get an admission. Try your best.
Hope it helps!

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