Topics
11. Chance
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AustraliaNSW
Stage 2

11.01 Describe likelihood

Lesson
Practice
Lesson

Are you ready?

What words can you think of that describe the the chance of something happening? Can you think of examples of events that fit each word you can think of?

Examples

Example 1

What is the chance my paper plane will fly forever?

A
Impossible
B
In between certain and impossible
C
Certain
Worked Solution
Create a strategy

Think about if a paper plane can fly forever.

Apply the idea

A paper plane must eventually land so it is impossible that it will fly forever. The answer is option A.

Idea summary

These are the 2 terms we have seen to describe chance:

  • Impossible: definitely will NOT happen.

  • Certain: definitely will happen.

Words to describe chance

This video shows us how to describe the likelihood of events.

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Examples

Example 2

What is the chance of flipping heads with a coin?

A table showing the heads and tails sides of a coin.
A
Unlikely
B
Likely
C
Even chance
Worked Solution
Create a strategy

Compare how often each outcome will happen.

Apply the idea

When flipping a coin, half the time it will land on heads and half the time it will land on tails.

Each side is equally likely to land face-up.

The correct option is C.

Idea summary

More terms to describe chance:

  • Unlikely: more likely NOT to happen than to happen.

  • Even chance: one thing is not more likely to happen than the other

  • Likely: more likely to happen than not to happen.

Order of chances

How likely something is can be visualised on a line similar to a number line. This video shows us how.

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Examples

Example 3

Which section describes the chance of 'the next person you meet has the same birthday as you'?

This image shows Impossible, Even chance and Certain on a chart. Ask your teacher for more information.
A
A purple square with lines on it.
B
A green square with lines on it.
Worked Solution
Create a strategy

Think about how often you meet someone with the same birthday as you.

Apply the idea

It is unlikely that the next person you meet has the same birthday as you.

An unlikely event will have a chance between impossible and even chance, which is described by the purple section.

The correct option is A.

Idea summary

In order of how much chance something has of happening, we can start from the left, and move right. It's just like a number line.

An arrow going to the right to show the order of chances from impossible, unlikely, even, likely, to certain.

Outcomes

MA2-19SP

describes and compares chance events in social and experimental contexts

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