That will only give you the right answer if all questions are equally difficult to answer based on how many marks they provide. This is never, ever ever, the case. Not because those who make exams are diabolical (they are) but because of the simple fact that it's your brains doing the questions, not a machine. Thus, while it may certainly be entertaining to find out how much time you can spend on each specific question based on an average calculated from the max amount of marks, it will also be incredibly useless.
Banned for making something very easy seem slightly complicated and presenting it in a stupid manner.