Most of times MBA aspirants are not aware of difference between percentile and percentage.
Let us understand that percentage is actually the proportion to 100 as reference figure. Thus 28 marks out of 40 mean 70% or 70 marks out of 100.
Now on percentile - suppose that your score on a test is in the 90th percentile. That means you scored better than 90% of the others who took the test.
It is perceived that in tough competitive exams like CAT which is taken by approximately two lac twenty thousand aspirants, percentile parameter works better way as exam is tough and students may not score that high individually so best among the entire group population can be selected for final GD & PI. Hence, it can also be said that percentile basis becomes tougher than percentage as you as student may lose the game by point one percent number also.
University exams and competitive exams have completely different matrix. In competitive exams you are competing with others and ensuring that you are not left out of competition whereas in university exams even if you score one percent higher or lower, you are passing through and are eligible for degree.