As per the eligibility to apply for CAT Entrance Exam you should have minimum 50% in your Graduation & for the reserved category such as Scheduled Caste (SC), Scheduled Tribe (ST) and Persons with Disability (PWD) you require 45%. You can check the further eligibility with the given below link.

https://bschool.careers360.com/articles/cat-eligibility-criteria

Good Luck!