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Year 9

Equally likely outcomes

I can state when outcomes will be equally likely.

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New

Year 9

Equally likely outcomes

I can state when outcomes will be equally likely.

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Share activities with pupils

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Lesson details

Key learning points

A set of possible outcomes can be stated.
Outcomes can be evaluated to decide how likely they are.
Outcomes with the same likelihood can be identified.

Keywords

Outcome - An outcome is a result of a trial.
Likelihood - Likelihood describes the chance that a particular event will occur.
Trial - A trial is a single predefined test.
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.

Common misconception

Rolling a 6 on a dice is less likely to happen than rolling other numbers. Or ticket 001 is less likely to be drawn in a raffle than other tickets.

The random nature of picking a raffle or rolling a dice means all outcomes are equally likely as each other.

Ask pupils to design a their own single-trial game where the likelihoods of winning and losing are equal.

Teacher tip

Licence

This content is © Oak National Academy Limited (2025), 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.

Select all the numbers that are multiples of 3.

0.3

Correct answer: 3

Correct answer: 6

Correct answer: 9

Q2.

Select all the numbers that are factors of 3.

0.3

Correct answer: 1

Correct answer: 3

Q3.

What fraction of the circle is shaded?

$${1}\over{3}$$

$${3}\over{7}$$

Correct answer: $${3}\over{10}$$

$${3}\over{13}$$

Q4.

In which diagrams is half of the circle shaded?

Correct Answer: An image in a quiz

Q5.

Jun wants to shade in $${1}\over{3}$$ of this whole circle. Jun should shade in sectors of the circle.

Correct Answer: 4, four, four sectors, 4 sectors

Q6.

Match each letter to the fraction of the circle that is labelled with that letter.

Correct Answer:a,$${1}\over{4}$$

$${1}\over{4}$$

Correct Answer:b,$${1}\over{3}$$

$${1}\over{3}$$

Correct Answer:c,$${5}\over{12}$$

$${5}\over{12}$$

Exit quiz

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6 Questions

Q1.

Match each key words with its definition.

Correct Answer:trial,a single predefined test

a single predefined test

Correct Answer:outcome,a result of a trial

a result of a trial

Correct Answer:sample space,all the possible outcomes of a trial

all the possible outcomes of a trial

Correct Answer:likelihood,describes the chance that a particular event will occur

describes the chance that a particular event will occur

Q2.

Complete the following sample space for the outcomes of the spinner. ξ = {A, I, L, R, }.

Correct Answer: T

Q3.

In which spinners are the outcomes 'win' and 'lose' equally likely?

Correct Answer: An image in a quiz

Q4.

Which outcomes are equally likely in this spinner?

Correct answer: A and B

A and C

B and C

Q5.

In which spinners are all the outcomes equally likely?

Correct Answer: An image in a quiz

Q6.

A regular six-sided dice is rolled once. In which sample space are the outcomes equally likely?

ξ = {factor of 6, not a factor of 6}

ξ = {multiple of 3, not a multiple of 3}

Correct answer: ξ = {odd, even}

ξ = {square number, not a square number}