So the calculation of Ranking,Cet rank and percentile is a bit tricky process so i try to explain it  to you with a simple example-

If you scored 120 in NATA and 80% in your boards, then the normalized score will be 120/2+80=60+80=140 also i suggest you to please try the rank predictor tool available on the careers360 website on which you can predict your overall rank and category wise rank very easily and can get the most accurate rank on your results.Lately you can also check your desired college or universities last year cutoffs for various courses and can effectively choose your dream college. Please check out this link for further reference-

Happy studying.