hi,

see isi entrance test question is only based on mathematics and some of apptitude question. there is two programs after 10+2 course you may apply for either in b.math or in b.state. if your basic mathematics concept is really clear and really study well in 10+2 course, then you can prepare for it for two months of hardworking. there is a book published by isi which is test of mathematics by 10+2 course, which has previous years entrance questions. you need to fully solve the paper to get the idea for the question difficulty level.