Any idea guys if its important? I havn't understood a word.. Has it ever been asked in the past exams?
Very dangerous to assume that if a topic has not been examined for many years that it will not come up in the paper you are sitting!
I just checked the 2000-04 papers as well. Not even once this topic has been examined and for good reason. It's a four page proof!
Technically, this proof only came into the syllabus in 2005 (if I remember correctly). However, it would be unusual to ask such a long proof - as it would require many marks on just one small aspect of the syllabus. The application is more important. The shorter waiting time proof (given in the exponential distribution section) was asked a long time ago. However, I have to say that they could ask it as it is in the syllabus...