IIM Ahmedabad - Indian Institute of Management Vastrapur Answered Questions

I would suggest that you write a mock CAT to figure out your strengths and weak areas. Depending on your score you can figure out when to start preparing. Its possible to score well in CAT by preparing rigorously for 4-5 months if your basics are good.
Know more about CAT at :
https://edudrona.com/common-admission-test-cat/#1464927769900-a0617f54-da37/?mref=tanu

There are usually two ways, by taking CAT and then WAT/PI. For second one, if you have lived outside India for at least 18 months and are away during CAT examinations, you can apply to IIMA using your GMAT Score. There is separate process for that.

Yes. Maths is very useful for CAT. One of the two papers in CAT checks your quantitative abilities. However majority of questions are from class 9th to 12th maths. Also you should not base your life decisions on requirements of one examination. If you think your time and energy are useful in other subjects than maths, I think you should take that up.

There is no fixed answer to this. However you are seriously disadvantaged in terms of your percentages. To make up for that you will have to score really well in CAT. In my personal experience you will need at least 99.7 - 99.8 percentile overall. However the criteria to compute composite score changes every year and also the scoring depends on the incoming batch. But in general with 99.7-99.8 percentile you should get more than one call from IIMs.

I don't think you will receive GDPI call from IIMs with 82 percentile in CAT. You will have to do really well and score atleast 99.5 percentile to get GDPI calls from atleast few older IIMs. Please understand that on an average 2 lakh students appear for CAT and 82 percentile means there are 36,000 students who have scored more marks than you. Seats in all IIMs combined is not more than 2000.

CAT exams are more about practice. It is more speed and accuracy than knowledge (unlike JEE). Questions are essentially very easy and if given sufficient time, you will be able to solve all the questions yourself. Hence you should focus more on practice under exam like situations. Post mock tests you should always evaluate what went right and what went wrong. Try to develop an understanding of your strong areas and the weak ones. Improve on weak areas and continue to do well on your strong areas.

Yes you can. As long as you are eligible as per the X,XII marks criteria (average &get;80 for Science, &get;77 for commerce, &get;75 for arts background), you won't be directly ineligible for IIMA.
But since your score is less in graduation, you need to compensate for the same by getting a higher percentile in CAT. Based on CAT 2015, you will require 99.8+ to be on the safe side for a call from IIMA.
All the Best!