Maths DLO.

Today I was learning to use data to predict outcomes and find outcomes using tree diagrams. For finding outcomes using tree diagrams I learnt to follow each branch of the diagram from left to right recording each outcome and for using data to predict outcomes  I learnt that data you collect can be used to make predication about a group or a population or anything the data's about. I found this task a little bit hard to begin with but as I worked through it it got easier. Something I need to work on is making sure I write down the questions before I write the answers. My question for you is why do you have to follow each branch for the diagram from left to right?