When a category has an Extra Credit (EC) item within it, the category score accounts the EC item as a regular item.
EC is an extra credit item out of 10 points. Exam is out of 100 points. Victor has a score of 0/10 for the EC and 100/100 for the Exam. His correct category score should be 100% ( (0+100)/100 = 100%).
Let's say he received 5 points in the EC item. His score should then be 105% ( (5+100)/100 = 105%). Currently it is calculated as 95.45%.