An I grade stands for incomplete grade which is being given to students under special circumstances amidst this pandemic. Obtaining an I grade means you get to take the final exam again. However, this has to be done in the immediate next semester. For instance, if you obtain an I grade in Spring 21, you must retake the final within Summer 21. Also, note that your pre-final marks will remain the same.
There are two reasons as to why you could've been given an I grade. First, it could be because you could not attend the final exam for unforeseen circumstances and your pre-final marks are decent. Another reason could be you took the final exam, but your total marks were below the passing threshold (40). However, instead of being given an F grade, you have been given an I grade because there is a possibility that if you prepare better and retake the final again, you will pass. Moreover, 50% of the marks that you obtained in your final have been added to your pre-final marks. For instance, if your pre-final marks were 23 and you obtained 10 in the final exam, then 5 marks (10*50% = 5) have been added to your pre-final marks, making it 28. This means that you need to score a minimum of 12 marks when you retake the final exam in order to pass the course. This is being done so that the marks that you obtained in the final are not completely discarded. Instead, a fraction of it will be carried over so that you have a higher likelihood of passing next time.
That depends. If you feel like your pre-final marks are not satisfactory and you want to retake the course from the beginning, then you will have to register again. That way you will be able to obtain new marks for quizzes, mid, etc. However, if you want to retake the final only, then you won’t have to register. This means you do not need to make any additional payments to retake the final exam.
Your course teacher may contact you or post a notice regarding this before the final exam. If that does not happen, then you need to contact them. My recommendation would be that you contact them early and ask their permission to attend classes. In this way, you will always be updated regarding what is taught. Otherwise, solely studying a few hours before the final may not be sufficient to overturn your I grade into a passing grade.
In the event that you previous course instructor is not teaching the course this semester, you need to find someone who does and request them to take your final exam.