Dear Ananya,

As you have asked this question 5 months ago and i hope you have got admission in decent engineering college this year.

If  you have  cleared  Class 12th this year then you can not appear for improvement exam in the same year for taking admission in same academic year. but if you wish to write one  or  a  few  subjects ( as you want to give improvement exam in 3 subjects only ) for 2019 academic session then the top 20 percentile cutoff for 2018 will be considered.

You can also appear for improvement  exam  in all the subjects , then the best of the two performances will be considered for 2019 academic session.

According to the Eligibility crietria for admission, you need to either score 75% aggreagte marks in Class 12th (for general category) or you should be in top 20 percentile.

Good luck!