Calculating theoretical probabilities from probability trees (two events)
I can calculate and use theoretical probabilities for combined events using probability trees (2 events).
Calculating theoretical probabilities from probability trees (two events)
I can calculate and use theoretical probabilities for combined events using probability trees (2 events).
Lesson details
Key learning points
- The probability of an outcome can be found with a probability tree diagram showing all possible outcomes for two events.
- The probability of a set of outcomes can be found using a probability tree diagram.
- The probability of a set of outcomes can be found using a probability tree, even when outcomes are not equally likely.
Common misconception
When I see a probability tree, I always multiply the probabilities.
If a probability tree shows a two-stage trial, then the probability of an outcome is the product of the probabilities of the outcomes at each stage. The probability of an event is the sum of the probabilities of each outcome in the event.
Keywords
Outcome - An outcome is a result of a trial (e.g. getting heads when flipping a coin once or getting two heads when flipping a coin twice).
Event - An event is a subset of a sample space. i.e. An outcome or set of outcomes that may occur from a trial (e.g. flipping a coin twice and getting the same result each time).
Probability tree - Each branch of a probability tree shows a possible outcome from an event or from a stage of a trial, along with the probability of that outcome happening.
Sample space - A sample space is all the possible outcomes of a trial. A sample space diagram is a systematic way of producing a sample space.
Licence
This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).
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