Hello,

See for ST, SC category min percentage required to get eligible for CAT exam is 45% and for OBC and general is 50%. As your aggregate 1st and 2nd year percentage is more than 45% or 50% so yes your are eligible for CAT exam.
Now the CAT registration date has been extended to 25th Sep. So please make sure you complete your registration before 25th Sep.
As less than 2 months are left for CAT exam so quickly brush up your basics and start giving lots of mock tests and analyse them. Analysing will help you in knowing about your strength and weakness. Also it will help you in overcoming your mistakes. You can also prepare a strategy for attempting your question paper. This will help you in increase your speed and accuracy whuch will lead to improvement in your marks and percentile. 
All the best!!

Hello , 

As your query is used diploma in commercial and computer practices and joint in second year degree after diploma and you are the student of final year now.

based on the question what you have written a mentioned above your question is kind of ambiguous and it's impossible for us to understand but if you can let me know in the comments section below what overall your question is and what you are looking forward for an eligibility then we can help you in better ways. 

Thank you.