In order to apply for CMAT Entrance Exam you should be Graduate with minimum 50% as a General cateory & 45% as a Reserved Category. You can apply for MAT & XAT Entrance Exam as there is no such boundations regarding percentage but still most of the colleges which give admissions on the basis of XAT & MAT score also keeps a minimum required percentage to be 50%.

With the less marks 50%, You can get the colleges which won't be of good reputation But still if you are really interested in pursuing MBA degree then try to get a very high percentile in XAT & MAT then you might have a chance in an average college.

Good Luck!