It says that all unsuccessfull exminers are divided into 10 groups with roughly equal numbers. I believe the higher bands are more concentrated than lower bands. If we suppose the lowest score has 40 correct answers and MPS is 80 correct answers, I guess band 10 is only short by 2-3 correct answers and the 2-3 shortage could go all the way down to band 7 or 6. Your thought?.
Going by 300hours analysis, 3-5 questions per band
http://www.300hours.com/blog/here-is-the-mps-estimate-for-cfa-level-ii-2012