In order to crack any exam you should be dedicated and self motivated. 

JEE is one of the competitive level exam you need to work smartly in order to crack your exam make proper strategy to acheive your goal 

There are many students who have cracked JEE exam without coaching

No.

BBA is not there in IITs as PG program in management like MBA is available in IITs like IIT-Kanpur.

Also, to check the top BBA colleges in India you can go through the below link -

https://bschool.careers360.com/articles/top-bba-colleges-in-india

Good Luck!!!

JEE Advanced maximum are not defined :

Maximum Marks vary every year like below:

2017- 366

2016- 372

2015 - 504

2014 - 360

So, it is difficult to predict marks as exam pattern and marks change every year but you should score more than 400% marks to get good

Please check the below names -

1. IIT Kharagpur
2. IIT Bombay
3. IIT Kanpur
4. IIT Madras
5. IIT Delhi
6. IIT Guwahati
7. IIT Roorkee
8. IIT Bhubaneswar
9. IIT Gandhinagar
10. IIT Hyderabad
11. IIT Jodhpur
12. IIT Patna
13. IIT Ropar
14. IIT Indore
15. IIT Mandi
16. IIT (BHU) Varanasi
17. IIT (ISM) Dhanbad
18. IIT Palakkad
19. IIT Tirupati
20. IIT Bhilai
21. IIT Goa

I get 91.5 percentile in cat 2021 which iit

Don't aim for Indian colleges.. Try to go abroad.. Canada, USA, Germany, Australia etc. These places will offer better educational options as well as a bright future after your degree completion.
Take it from me... even though I'm in NIT, life isn't any better.

You should plan your study accordingly. Make your time-table according to your comfort. Include all the topics from your boards and entrance exam. Set your daily and weekly targets. 

Give proper attention to the topics which carries more weightage in the exam. Try to solve MCQs related to them. 

You

The cut off varies college to college and fluctuations in the same are there category, branch and year wise. Also, there is no information out for Gate 2018 cut off so it is advisable to get a rough idea about the cut off trend by going through the below link-