M4.6.4 For the adult
Tree diagrams
A bag has 3 red and 2 blue counters. I take one, look, put it back, and take another. What is the chance of one of each colour?
What this chapter teaches
A tree diagram follows events in order. The branches from one point add to 1. Multiply along a path for "and", and add the paths that end in the event for "or". All the ends together add to 1, which is a good check.
Three questions to ask
There is no one right wording. Listen for the idea.
- Why do the branches from one point on a tree add up to 1?
- Why do you multiply along a path but add between paths?
- A coin is tossed three times. How many ends does the tree have, and why?
After the chapter, the learner can
- Draw a tree diagram for two events
- Find probabilities by multiplying along the branches
What they copy into their notebook
A tree shows events in order. Branches from one point add to 1. Multiply along a path. Add the ends that make the event. All ends add to 1.