Hello

CAT eligibility criteria says that:

To be eligible for CAT ,
you need a  Bachelor's degree with at least 50 per cent marks or equivalent CGPA  while those who are from SC/ST/PH category need only at least 45 percentage in Bachelor’s Degree in any discipline to be eligible

So , it is your score or % obtained in graduation which is considered for CAT eligibility and not that of post graduation ,so one cannot be eligible for CAT on the basis of score or percentage of obtained  in the post graduation

Now ,

You have got 49.5% in your graduation ,so you are not eligible for CAT if you belong to General or OBC category but if you belong to SC/ ST or pH category then you are eligible for CAT examination

For detailed information go through
https://bschool.careers360.com/exams/cat

Thank you