Entrance Exam

Today I was talking to one of my close friend.. Her elder sister's PG in Medical entrance exams results were supposed to come.. but sad.. the governing body have changed the rules.. and so there is a stay..
They are thinking to take MBBS results in to consideration for PG seats..

I remember my student days.. Once we had a subject called "Electronic Components & devices". I had some idea over it..and being over confident I did not study that paper and got avg marks.. I was expecting very good scores out of it.. After the results came I felt bad about it.. and in the holidays I studied that paper again. And without any prep I was able to explain the subjects to my juniors..

If I was supposed to evaluate my standard.. how much I rate from 0 to 5 can I rate my self 3 based on my last exams result or I should rate 5 for my understanding on the subject?

If I feel I should rate 5 then why in the above PG entrance exam, they should consider MBBS marks even after taking the test? Are not they confident on their entrance exam questions?