decision tree

If you state what your problem is on here then I will try and help. (Have you watched the lecture on here on decision trees?)

no I haven't but I don't know how to access it can please give me directions on that?

If you click on ACCA (on the bar at the top of this page), then you will get a page with a heading not too far from the top 'Free ACCA Course Notes and lectures'. Below it is a list of the papers and if you click on F5 then you will get a list of the resources (including the lectures).

Is it just me or is it really confussing to know when to put a square and when to put a circle on the decision tree!! I have done several questions on it and they never seem logical to me!!! How do you know when it's an outcome and when it's a decision? I know it should seem obvious but if you could provide a basix example that would be great..... Many Thanks

You can use any symbols you like (but do show a key in the exam). I use a square when it is our choice, and a circle when it is uncertain. For example, if we have to choose between two machine, then it is our choice which to pick and so I would use a square. If there were two possible returns from one of the machines, with different probabilities, then it would not be our choice which return we got - it would be uncertain. And so for the two possible returns I would use a circle. There is a basic example in my lecture on here which draws the whole tree.