BHMS

I have no idea about cut-off rank but By 50th percentile, it means that your marks in NEET 2018 should be such that your marks come in top 50% of the candidates who will appear for NEET 2018. Similarly, 40th percentile will mean that you should score such that you come in top 40% of the candidates who will appear for NEET 2018. It is difficult to give exact marks which you must aim in NEET 2018 in order to qualify/pass the exam, since a lot will depend upon preparatory levels of other candidates, number of aspirants, etc. But, you may get a rough idea of the same from previous year NEET cutoff data. In 2018, the equivalent score of 50th percentile (passing marks) was 131 out of 720 for general category and 107 something for reserved categories. I suggest you aim to score at least above 200 in order to pass NEET 2018 and become eligible for admission in BHMS course.