(KS3, Year 7)
The LessonA probability is a measure of how likely (how probable) an event is to happen. A probability is expressed as a number between 0 (impossible) and 1 (certain).
Dictionary DefinitionThe Oxford English Dictionary defines a probability as "the extent to which a particular event is likely to occur... expressed by a number between 0 and 1.
The Probability ScaleProbabilities express how likely an event is to happen on a scale of 0 to 1.
- An event with a probability of 0 is impossible: it can not happen.
- An event with possibility of 1 is certain: it will happen.
Expressing ProbabilitiesA probability can be expressed as:
Lesson SlidesThe slider below explains more about probability. Open the slider in a new tab
A Note on NotationThe probability of an event can be written as:
P(Event)A letter or symbol can be used to represent an event. For example, let H be the event that a coin lands on Heads when it has been tossed. We can denote the probability of getting heads as:
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