It is not only this time. Such marks were scored in prior attempts as well.
One basic reason for students not able to score high marks in costing paper is the inability to attempt all questions in this paper. If a student can attempt 100 marks in this paper, scoring 70-80 is not at all difficult. It requires conceptual clarity, consistent practice and composed mind during exams
This paper generally has a couple of questions which the students would have seen for the first time. It does not mean that the questions are not attemptable. The issue is students on seeing a new type of question panic and lose control over the exams. This has happened attempts after attempts.
I would like to share our attempt way back in May 2007. The paper was completely unexpected. Two questions from one chapter (One was never seen before by many) followed by a theory question on Activity Based Costing (generally it used to be a 8 marks practical question) and one question in FM which was slightly modified version of a question asked in final (based on financial ratios - U can understand the level of difficulty).
Everything went like a bouncer for almost everyone in the hall. Everyone had worried faces after the paper and one could make out what had happened. The aftermath was about 30% students absent for the next paper.
Let me share you the feedback from students after the exams -
Most were of the opinion that had they maintained their cool in the exams, they could have easily managed 70 marks in the exam. The problem based on financial ratios was solvable with some thought (12 marks), the unique question on operating costing was also solvable had they given a little thought and could actually imagine it as a real life scenario.
Just because of panic, many could not attempt the paper the way they could have.
This is one of the important factors for scoring good marks in exams.