 # Using the Probability Scale

In this worksheet, students practice placing probabilities on a scale. Key stage:  KS 4

GCSE Subjects:   Maths

GCSE Boards:   AQA, Eduqas, Pearson Edexcel, OCR

Curriculum topic:   Probability

Curriculum subtopic:   Probability, Basic Probability and Experiments

Difficulty level:   ### QUESTION 1 of 10

Probabilitiy is all about finding the chance of something happening.

One thing you will be expected to do is to say which of two events is more or less likely.

To do this, we use the probability scale. There's a couple of things to notice here.

The scale starts of at impossible at the left and gets more likely unitl we hit certain at the right.

The probability scale starts at 0 (impossible) and ends at 1 (certain)

We'll focus on the numbers later, let's just look at words today.

Examples: On the probability scale above, where would you place the following events.

1) You throw a coin and get a head.

Ans: This is an even chance, so it would go at point D.

2) You roll a dice and get a 6.

And: This is very unlikely so it would go at point B

You cannot have something that is more likely than...

You cannot have something that is less likely than...

On this probability scale, match the situation with the letter. ## Column B

Winning the lottery
B
You doing some maths today
F
A 15 year old owning a phone
G

Which two of the letters on the scale could you use to describe getting a 5 when you roll a normal dice? Make sure you select two options.

A

B

C

D

E

F

G

Which letter on the scale could you use to describe getting an odd when you roll a normal dice? A

B

C

D

E

F

G

Which letter on the scale could you use to describe getting a 7 when you roll a normal dice? A

B

C

D

E

F

G

Which word would you use to describe an event at point E? Which word would you use to describe an event at point G? Which event is more likely? One at point C or one at point E? C

E

Which event is less likely? One at point E or one at point F? E

F

• Question 1

You cannot have something that is more likely than...

EDDIE SAYS
The most likely anything can ever be is certain.
• Question 2

You cannot have something that is less likely than...

EDDIE SAYS
The least likely anything can ever be is impossible.
• Question 3

On this probability scale, match the situation with the letter. ## Column B

Winning the lottery
B
You doing some maths today
G
A 15 year old owning a phone
F
EDDIE SAYS
Winning the lottery is very unlikely You doing some maths today is certain (You're doing some now) A 15 year old owning a phone is very likley (Its definitly not certain)
• Question 4

Which two of the letters on the scale could you use to describe getting a 5 when you roll a normal dice? Make sure you select two options.

B
C
EDDIE SAYS
We could describe these options as either likely or very unlikely. You could use either B or C
• Question 5

Which letter on the scale could you use to describe getting an odd when you roll a normal dice? D
EDDIE SAYS
There are 3 even numbers and 3 odd on a dice. This gives the chance of getting an odd as an even chance. (D)
• Question 6

Which letter on the scale could you use to describe getting a 7 when you roll a normal dice? A
EDDIE SAYS
There isn't a 7 on a dice so this has to be impossible.
• Question 7

Which word would you use to describe an event at point E? Likely
likely
EDDIE SAYS
E is above the middle bit closer to the middle than the right, we should call this a likely chance.
• Question 8

Which word would you use to describe an event at point G? certain
EDDIE SAYS
This is at the very right so this is an event that is certain.
• Question 9

Which event is more likely? One at point C or one at point E? E
EDDIE SAYS
As we move to the right, the events become more likely.
• Question 10

Which event is less likely? One at point E or one at point F? E
EDDIE SAYS
As we move to the left, the events become less likely.
---- OR ----

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