Page 98 - Knowledge Organiser Yr8 24-25

Knowledge Base: Mathematics TOPIC 17: Probability Year 8 | Spring Term 1
By the end of this topic, you should be able to:
• Construct and use a probability scale
• Calculate probability as a fraction, decimal or percent
• Calculate theoretical probability
• Know the 1-P rule
• Calculate experimental probability
• Compare experimental and theoretical probabilities
• Understand the terms mutually exclusive and exhaustive
Probability Even chance
Event Trial
A measure of the chance that an event happens A 50% chance of happening
A set of outcomes
An activity within an experiment
The probability of a flipped coin showing
tails is 1⁄2 or 0.5 or 50%. This is an even chance
An even number: 2, 4 or 6 is the event Flipping a coin is a trial
Language
Meaning
Example
Equally likely
Events with the same chance of happening
For a fair dice 1, 2, 3, 4, 5 and 6 are all equally likely. The probability of each outcome is 1/6
Outcome
One of the results which could happen when you carry out a trial
For a dice 1, 2, 3, 4, 5 and 6 are the outcomes
Experiment
A series of trials which can be used to estimate a probability
Rolling a dice 600 times to see if it is biased is an experiment
Biased
A trial in which all the individual outcomes are not equally likely
A coin which shows heads twice as often as a tail is biased
Mutually exclusive
Events that cannot both happen together
Raining and not raining are mutually exclusive events
Important things to remember:
P(A) is the probability that event A occurs
The probability that event A does not occur is 1 – P(A)
Exhaustive
All the possible outcomes of a trial
An ‘even’ score and an ‘odd’ score on a dice
Relative frequency
As estimate of probability from experimental data
Weather forecasters use patterns to estimate the probability of rain
Worked examples
98