test percentage

Most sections give a range of point values 5-10 but is there an approximation somewhere with an approximation % based off of previous test? My friend did a mean average like 7.5 in this case, another friend added all the max points and divided by the total number and got an approx percentage. Is there a good algorithm to predict the approximate percentage of questions from each section? i understand nobody every exactly knows but looking for some logic to weighting each topic.

i wish i knew, i asked this question many months ago. hopefully someone has some insight to this and comments