Hello Chandan

It would be difficult to tell the exact rank required as the cutoff vary every year depending on various factors. Performace  in the common entrance test and qualifying exam both are considered in equal proportions. So, you must also score well in the qualifying examination.
However, you can go through the link below and check the previous year cutoff for refernce and to have an idea about the marks required.

http://kea.kar.nic.in/cet_2018.htm

Good Luck!