Hello Mrinal

It is difficult to predict the actual rank or JEE Advanced qualifying marks as for the first time JEE Main is being conducted twice and rank will be based on NTA percentile score but you may calculate your expected rank by this formula-



874469 are the number of candidates appeared for the January exam. So rank formula is (100- your total percentile score) * 874469 / 100.
If the number of candidates for April exam increased to 1400000 then your final rank shall be (100- your total percentile score) * 1400000/100

You can calculate your marks from the answer key which was released by NTA. Link to the JEE Main answer key-

https://engineering.careers360.com/articles/jee-main-answer-key

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Good Luck!