IIT

Try analytics companies, if you have studied stats as well. Else learn what all is required in the job and then apply - there are quite a few openings. You will need thorough knowledge of - linear and logistic regression, data mining and processing etc. In tools - often different companies use different - try learning SQL
- one among SAS or R ( R is free but SAS is expensive and more convenient and widely used, however now certain companies are switching to R as well, since it is free)
- Knowledge of Excel and VBA - might be helpful. If you really know maths/stats - you can try learning about Machine learning higher level algoriths also.

Yes, it's definitely proving to be best since a couple of years. 57 in 1000 ranks in JEE Advance is worth noting. Surely, Kotak Centre is the good one. If you really want to join Vidya Mandir then try avoiding other centers and go for Kotak Centre.

I think NIT- Allahabad is better with ECE. There, you will get a good atmosphere of coding and ECE is one of the top branch of NIT-Allahabad. NIT-Allahabad is better in all manners.

Admission:
Candidates qualifying in the JEE Advanced are eligible to admission in the 23 IITs if they satisfy any one of the following criteria. They should score a minimum of 75% in the class XII board examination.

You'll need to qualify through JEE Main and JEE Advanced and you can get admission for first year of four year degree course. [Many state or private colleges will admin Diploma holder in second year directly, but not the IITs or NITs.]
Diploma holders are eligible to get direct admission in second year of B.Tech through different CETs of state governments.

Hello,
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For some universities, they ask for qualifying marks, some of the universities accept 75 as qualifying marks, but for the top best universities /colleges, 150 scores or above is the best. You can try for National Institute of Technology Calicut (https://josaa.nic.in/webinfocms/public/view.aspx?page=46) Chandigarh College Of Architecture, Manipal University, BIT Mesra, Lovely Professional University-Punjab, Sushant School of Art And Architecture - Ansal University.

If we talk about B.Tech then it is fine to do from private university but renowned, M.Tech from IITs need certain criteria for that, you have to prepare well during graduation. For B.Tech you can try for SRM University, Lovely Professional University and Amity University as you need to groom your skills much so that you do not face concern after M.Tech.

To get admission in IIT for architecture in Bachelor's degree first of all you will have to clear JEE Mains paper for architecture and after clearing the Mains paper you will have to clear JEE Advanced with good marks to get into any of top IIT'S, then you will be able to get the IIT from counseling.

IITs don't have marine engineering streams till now. They have ocean engineering and naval architecture, which is different from marine engineering.