Hi. As per your question, for 30-40 marks, the percentile will be in between 58-71. You can go through the link below to get an estimate about the percentile for various range of marks. The ranks have also been mentioned there. Your rank must be in between 2,60,000 - 3,80,000.
https://engineering.careers360.com/articles/jee-main-marks-vs-percentile
Regards.
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