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Year 9

The scale of likelihoods

I can show the likelihood of an outcome on a scale.

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New
New
Year 9

The scale of likelihoods

I can show the likelihood of an outcome on a scale.

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Share activities with pupils
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Lesson details

Key learning points

  1. A scale can be drawn showing the 5 different likelihoods.
  2. The likelihood scale can be evaluated to understand why only 5 states are shown.
  3. Different outcomes for an event can be placed on the likelihood scale.

Keywords

  • Impossible - An outcome is impossible if there is no possibility that it can happen.

  • Certain - An outcome is certain if it is guaranteed to happen.

  • Even chance - An outcome has even chance if its likelihood of happening is the same as its likelihood of not happening.

Common misconception

'Equal chance' means the same as 'even chance'.

When a trial has more than two possible outcomes which are all equally likely to happen, each outcome has less than an even chance of happening. E.g. each number on a dice has the same likelihood of being rolled, but each is less than an even chance.

Present pupils with a spinners, set of cards, dice or other equipment. For each piece of equipment, ask them to come up with some events that are unlikely to happen and some events that are likely to happen. They could then conduct lots of trials with it and see which events occur most often.
Teacher tip

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).

Lesson video

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Starter quiz

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6 Questions

Q1.
__________ describes the chance that a particular event will occur.
An event
Correct answer: A likelihood
An outcome
A sample space
A trial
Q2.
Which statement is true for this spinner?
An image in a quiz
The most likely outcome is for it to land on 'lose'.
Correct answer: The most likely outcome is for it to land on 'win'.
The two outcomes are equally likely to happen.
Q3.
Which letter is this spinner most likely to land on?
An image in a quiz
a
b
Correct answer: c
Q4.
Select all the multiples of 4.
1
2
Correct answer: 4
Correct answer: 8
Correct answer: 12
Q5.
Select all the factors of 4.
Correct answer: 1
Correct answer: 2
Correct answer: 4
8
12
Q6.
Select all the prime numbers.
1
Correct answer: 2
Correct answer: 3
4
Correct answer: 5

Exit quiz

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6 Questions

Q1.
An outcome is __________ if there is no possibility that it can happen.
certain
even chance
Correct answer: impossible
likely
unlikely
Q2.
Which statement describes the meaning of 'even chance'?
An outcome has less chance of happening than not happening.
Correct answer: An outcome has the same chance of happening as not happening.
An outcome has a greater chance of happening than not happening.
Q3.
Match the words with their positions on the scale of likelihoods.
An image in a quiz
Correct Answer:A,impossible

impossible

Correct Answer:B,unlikely

unlikely

Correct Answer:C,even chance

even chance

Correct Answer:D,likely

likely

Correct Answer:E,certain

certain

Q4.
Match each event with the term that describes their likelihood.
Correct Answer:Rolling 1,2,3,4 or 5 on a 6-sided dice,likely

likely

Correct Answer:Rolling a 6 on a 6-sided dice,unlikely

unlikely

Correct Answer:Rolling an odd number on a 6-sided dice,even chance

even chance

Q5.
A bag contains counters that are each labelled with a letter from A to C. One counter is chosen at random from the bag. Which term describes the likelihood of choosing the letter 'A'?
An image in a quiz
certain
Correct answer: even chance
impossible
likely
unlikley
Q6.
A regular six-sided dice is rolled. Starting with the least likely, sort the events in increasing order of likelihood.
1 - rolling a negative number
2 - rolling a multiple of 6
3 - rolling a square number
4 - rolling a prime number
5 - rolling a factor of 6
6 - rolling an integer