Yes, all you need to do is focus on your CAT score and score around 99.5 or more.
The first stage for admission is the PI rounds which take place on the basis of your composite score. The composite score has
CAT score
Class 10th score
Class 12th score
Gender Diversity
Your class 10th and 12th scores will be calculated as follows
Class 10- Greater than or equal to 80 gets 10 marks
Class 12- Greater than or equal to 70 gets 6 marks.
This score is not a bad one and still can get you into IIMC as long as you get a high CAT score.
For the next round, your work experience comes into consideration. Your above-average 10th marks and average or below average 12th marks demand a high CAT score along with above-average work experience to get into IIM Calcutta.