Your tenth percenage is going to be a hurdle while appearing for IIM interviews and gd. Your 12th marks are good. So yes it is possible for you to get into IIM calcutta. All you have to do is maintain a good academic record in your graduation. Do some social work, extra curriculars and gain a good number of certificates. You could also strengthen your profile by doing some financial certifications like ca, cs, etc. After you have done this give CAT exams and score above 99.7 percentile in CAT and you will surely get a call from iim calcutta. Rest is then left on your interview skills and group discussion.