well actually I think the minimum passing score is definitely below 70%, I assume it is between 55% and 60% which explains why the pass rate is higher.
But still i'd like to point out that even if some have 4th quartiles somewhere it is completely understandable to see a pass mark. As you can see and specially for part 2 you have 25% for each of the three major topics (credit market and operational) and then 15% for investment management and 10% for current issues. This means that if you have 4th quartile on a 15% or 10% weight, it is less dangerous than a 4th quartile on any other 25% weight topic.
Plus you dont know where you are in this quartile, so a second quartile could mean you outperformed 50% and up to 74.9% of other candidates which can explain why a candidate may pass when they are in the higher end of the range. (maybe conservative to assume the middle of the range)
As witnessed from many candidates, sometimes quartile performance is close and you have different results (pass/fail), I would assume the reason is score being either the higher or lower end of the quartile range.
anyway congratulations to all who passed, i found the curriculum very interesting and challenging. good luck to all candidates for November, i am sure that with little working experience and reasonable study time and understanding of core concepts, a pass mark is highly likely.