I would appreciate if Mr. John Lee comment on question 2 (the probability of ruin one).. This question has made me restless..
It has been a while since I sat ct6, but you would assume if you can calculate the answer without the use of approximations, which you can, then that is the correct way. The cdf of the exp distribution should be assumed knowledge and can be used to evalute the probabilities needed. If you used approximations you could still get method marks etc though. You did your best and it is time to think ahead and try to forget about this sitting now.
