 # 11.01 Describe likelihood

Lesson

## Ideas

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

Impossible means that an event cannot happen.

Certain means that an event will definitely happen.

## Words to describe chance

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

### Examples

#### Example 2

What is the chance of flipping tails with 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

If an event has an even chance of happening, then it is likely to happen half the time.

## Order of chances

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

### Examples

#### Example 3

The events A, B, C and D have probabilities as shown on this probability line:

a

Which events are more likely to occur than event B?

A
Events A and C
B
Events C and D
C
Events A and D
Worked Solution
Create a strategy

Find which events are to the right of event B.

Apply the idea

The events that are further to the right on the scale than event B are events C and D. So the correct answer is Option B.

b

Which events are less likely to occur than event C?

A
Events A and B
B
Events B and D
C
Events A and D
Worked Solution
Create a strategy

Find which events are to the left of event C.

Apply the idea

The events that are further to the left on the scale than event C is event A and B. So the correct answer is option 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.