其實機會很微
詳情可看看
http://beanactuary.com/exams/cbt.cfm 最底:
The unofficial instant pass/fail results received by candidates after they complete a CBT exam have been extremely reliable since the SOA/CAS/CIA began this practice in February 2007. As of July 2009 only 1 out of 39,656 candidates has had an issue with the unofficial instant pass/fail result not matching the official final score result. Candidates can be very confident that their unofficial pass/fail result will match their official final scores.
差不多可以說是almost surely 不會有差異;那人我想是因為 ambiguity/ defective of question 從不及格變成及格吧