To be honest, your class 12th marks doesn't matter that

much as they only need to make you eligible for a particular

exam.

But, you'll have to work pretty hard to offset that 12th score.

To be good enough for you will most importantly need 99.5+

percentile in CAT and good enough marks in your graduation

too.

Though you have to keep in mind that there are some top

IIMs which are strict for their 10th, 12th criteria, do not

keep many hopes from them.

Good luck!