Now the question is: Are “Production cost” and “Selling price” independent? Not if they are influenced by some common uncertain factor. The main contributor to the production cost and the selling price is the number of chocolate bars produced and sold. Assuming that we are able to adjust the production to the demand, we can represent this quantity by a single node which we will call “Number of chocolate bars”.

Create a new node by clicking on the “Independent” button in the toolbar.

Name the new node “Number of chocolate bars”, either by editing the name field in the dialog box, or by activating the title field. (Most likely you will find the latter method a little bit more convenient.)