JEE Main

For NITs and IITs you need 75% + but there are some low colleges which expects less percentage. Go to shiksha's website and find colleges with less eligibility marks.

JEE Mains cut-off trends:
2017-81 marks
2016-100 marks
2015-105 marks
2014-115 marks
2013-113 marks
Anything above this you should qualify for counselling in govt. engineering colleges. As competition is fierce, you should secure high marks to qualify for the merit list of the top NITs.
Here are the most important factors that help derive JEE Main Cut off each year:
Total number of appeared candidates
Difficulty level of exam
Previous year cutoff
Number of available seats
Overall performance of the candidate

It depends on how are you preparing each subject. Yes, giving your 100% in all the three subjects you will top the JEE Mains. Try to do self-study for 6 to 7 hour per day. All the best!

VIT and VTU are the famous universities for engineering studies.

Hello Ayush,
No, unfortunately, no. You will have to appear once again in 2018 for JEE Mains.

Hello Atharva,
SAT & JEE Mains are two of the toughest exams. Both are for entry to graduate courses. I feel both are equally tough. My opinion is JEE Mains is a little tougher than SAT. But it sure helps if you are attempting both.
Best wishes!

Yes, you could get admission but the dates of admission are over.

Yes, you can get admission based on your JEE Mains marks.