Checking for percentage of getting a certain score is based on math not guess work. The possibility of something happening is also based on calculations. Let's say there is a position open for admission and 10 people applied. You have 1 in 10 chance of getting in, that is percentage of success you have. Let's say you apply, either you get in or you don't, either a yes or a no, the possibility of you getting in is 50/50 so you have 50% chance of getting in.
If you were to go to a fortune teller or reading some cards of your chances of getting in, that would be shirk.