This is one of the most frequently asked questions by prospective MBA students. Students often wonder if their low graduation scores will fetch them calls from top B-schools like IIMs or FMS.
You will be glad to know that IIM Calcutta and Bangalore along with many baby IIMs give out calls to students who scored 50 to 60% in their graduation or have an average academic profile. The reason they were able to make it into IIMs despite a low graduation score is their excellent performance in CAT and the interview round which compensated for the average academic profile.
IIM Calcutta has quite a few students that scored only 60% in graduation.
Overall, I would suggest you place maximum emphasis on the CAT preparation. Ace that exam and you will be good to go.