2009 Track Circuit Question

[PJW]

I raised the issue with the invigilator during the exam, he came back to me and said that there was a worked solution to the question, and said he couldn't comment as he hadn't done the maths himself, which is fair enough, but does suggest a typo rather than a dirty trick.

Let's just say that it sounds that there seems to be some egg on the face of the examiners; there seems to have been errors rather than a "dirty trick". It is too late for the candidates to worry about what to do with the question; it is the turn of the examiners to do that. Could be an interesting Exam Review in January .....