The figure below shows for each PI what percent of the students have a performance of more than 60, more than 70, more than 80, or more than 90. For the students with PI < 0.5 (rounds to PI=0.0 in our graph below), almost all the students have a performance greater than 60, the top left point in our graph. About 98% have a performance greater than 70. Around 90% have a score greater than 80 and a good 70% score above 90. On the flip side only 5% of so students with a PI>0.95 have a performance greater than 90. Only about 30% have a score greater than 60. So in effect 70% of students in this group, fail the assignment grade in the class.