Both B.Stat and B.Math are different courses being offered at different campuses at ISI Kolkata and ISI Bangalore respectively. There are only a few common subjects in both courses. 

The choice ultimately depends on your choice and interest. You can go through the syllabus of both courses and understand the topics. Find whichever interests you, you can choose to be research-oriented like B.math students or go for M.stat or other courses, if you choose so.

You can apply for only 1 course because the institute conducts the entrance of both courses at the same time and day. You will be able to appear for only one of them.

There are three sections in the entrance exam and the level of maths is the same as what you studied in your 12th. The exam follows the pattern of most high school mathematics competitions (RMO, INMO, etc).

The three sections of the Entrance Exam consist of MCQ, A Subjective Test, and an Interview.

The books you must know are:

1. Problem Solving Strategies by Engel Arthur
2. Test of Mathematics at the 10 + 2 level, Indian Statistical Institute, Published by Affiliated East-West Press Pvt. Ltd.
3. Challenge and Thrill of Pre-College Mathematics by B. J. Venkatachala

You should complete these all and do previous year’s papers of ISI/CMI RMO, INMO and IMO.

For Interview:

• Once you crack the exam, the interview part won’t be that difficult.
• Answer the questions confidently and honestly.
• The entrance exam of ISI is not easy and also there are only a few seats for B.Stat. 
• You have to prepare well.

Do not overthink and do your preparation well. This will help you a lot. Be calm and try to think of cracking the exam and the latter part would be an easy task for you.

ISI Kolkata is considered to be a good institute for B.Stats. It accepts admission purely on the basis of the entrance exam and the interview. The minimum eligibility criteria for the entrance is 70% in class 12th boards. 

The selection process will be finalized upon your performance in the entrance exam and the interview session. With this score, you will be able to pass through the cutoff but you must have an exemplary performance during the interview session.

President University:

Presidency University is ranked at 151st position by National Institutional Ranking Framework in 2020. The graduation program is of 3 years where the tuition fees to be paid is 2,125/- per year. This university has a legacy of 200 years and it is well established.

Eligibility & Selection Criteria:

• Students seeking to obtain admission at this institute must have completed 10+2 with 70% in Physics, Chemistry, Mathematics and Biology from a recognised school.
• Students are required to appear in the Presidency University Bachelor Degree Entrance Test (PUBDET) which is followed by counselling.

Placement:

• Top recruitment firms like Deloitte, Mu Sigma, TCS, HSBC and many more visit the campus for placements. 
• Overall placement percentage of the institute is 70%. 
• The average package which a graduate receives is 5 lakh p.a. whereas the highest package offered is 13 lakh p.a.

Amity University:

Coming to Amity University, the fees structure for BSc 76,000/- per year, which is relatively very high when compared to Presidency University. This was established in 2015, but it has a world class campus at par with Ivy League Universities.

Eligibility & Selection Criteria:

• To obtain admission, the student must have a 50 % aggregate score in class XII. Students should also have a minimum score of 50% in Statistic or Maths.
• English test is conducted by the university to check the language proficiency of the student, which is followed by the Personal Interview.
• Scholarship provided by the University based on the score of 10+2 are:

Placement:

• Top recruitment firms like Amazon, Byju’s, Indigo, Deloitte and many more visit the campus for placements. 
• Overall placement percentage of the institute is 90%. 
• The average package which a graduate receives is 5 lakh p.a. whereas the highest package offered is 24 lakh p.a.

Anyone who is ready to invest a good amount of money in their education and great infrastructure can choose to study at Amity University as they have got the better placement percentage and have brilliant companies coming to recruit at their campus. Presidency University as well offers good placement and they have comparatively very less tuition fees.

My brother appeared for the interview last year, so I think I can answer your question.

The panelists will evaluate your ability to explain new questions. They might even ask you to solve the questions on the board. You must be clear about your choice of ISI Kolkata as you will be asked the reason for the same during the interview.

Expect questions on topics such as Calculus, Geometry, Combinatorics, and Probability. Keep your basics clear, know the definitions, and practice solving problems based on the definitions.

Just keep practicing, be confident and give your best shot at the interview.

Both the above-mentioned options are excellent to be considered. The IIMs prepares you to manage people and processes, whereas the ISI prepares you to be excellent quants.

Many IIM graduates work as quantitative analysts, they get the highest-paying jobs. If the ISI course is more appropriate, you could take the Bachelor of Statistics course. Quantitative analysts, on the other hand, tend to wear out soon, due to heavy workload.

An IIM education provides you with a broad perspective on management as well as access to a large alumni network. So, if you want to work your way up the corporate ladder, an IIM would be a better option. At the end of the day, it's up to you to decide where your priorities lie.

The path you want to get into is a very dangerous one and it can totally spoil your career without you being able to do anything for it. 

ISI, B.Stat is a very famous course and is known for the entrance paper which is considered very tough by all those appearing in it. The course is tough because the student who is above the cutoff receives a huge financial help from the government covering the major portion of the tuition fee. Apart from this after the entrance exam the candidate can be certain of a well paid job one he/she completes the course and is awarded with the degree.

It gets difficult for the selections if there’s a year gap as lower age students are preferred and in your case there's a two year gap so the chances reduce even more. It would be very risky to change your college again and could cost some harm in your career.

Both colleges are great options for studying statistics. 

Presidency University has a glorious history and the department of Statistics is one of the best departments. The university has great alumni which makes it score higher in terms of ‘Heritage’. One of the most famous names among them is P.C. Mahalanobis. There are dedicated faculty members like Prof. BR and Prof. PD, who is an alumnus himself. 

One of my friends has Statistics as his electives but he never got the chance to be taught by these reputed faculty members. Students are highly dedicated and excels in their respective university exams.

Graduates from this college pursued post-graduate studies from reputed universities like ISI, CMI, IMSc, etc. If you have Honours in Statistics with Mathematics and Economics, then it will be a great combination.

In terms of environment, you will get a sense of freedom at Presidency and a change to form a opinion on various aspects of life. However, St. Xavier’s College is also good but it is very strict and you will get a feel of school there. It is known for its discipline while Presidency University is know for its creativity.