# Introduction to Probability

In this worksheet, students practise using words to describe probability.

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

What is probability?

Probability in maths is the area that deals with the chance of something happening.

What words do we use to describe probability?

There are 7 terms we use to describe probability;

Impossible: There is no way this can happen (Example: A man growing to be 200 ft tall)

Very Unlikely: This will probably not happen but could. (Example: Winning the lottery)

Unlikely: This has more chance of not happening than it does of happening (Example: Rolling a six on a dice)

Evens: This has two things that could happen that are equally likely (Example: Tossing a coin and getting a head)

Likley: This has more chance of happening than it does of not happening (Example: Picking a constonantout of the alphabet at random)

Very Likely: This will probably happen but might not. (Example: You using your phone today before you go to bed)

Certain: This has to happen (Example: Rolling a normal dice and getting a number less than 7)

When do I use words to describe probability?

Most probability is described using a number so you should only use words if the question says to.

Match the situation with the word you would use to describe the chance of it happening.

## Column B

You will watch some telly tonight
likely
You will live to be 100
unlikely
Christmas day will be oon the 25th December
Certain
A new born baby will be a boy
Evens

What word would you use to describe...

The chance of you having a english lesson today.

Likely

Certain

What word would you use to describe...

Picking a card out of a deck of cards and getting a red card

Likely

evens

What word would you use to describe the chance of picking a red ball out of a bag containing only red balls.

Which of these two events is more likely

Event A: Rolling a normal dice and getting a number less than 7.

Event B: Rolling a normal dice and getting an odd number.

Event A

Event B

Which of these two events is less likely

I have a bag with 7 red balls and 3 black balls

Event A: Pulling out a black ball

Event B: Pulling out a yellow ball

Event A

Event B

Is it an even chance that it will rain tomorrow?

Yes

No

Does the probability word correctly describe the situation.

Which of these events are likely?

Winning the lottery

A child eating cereal for breakfast tomorrow

You will live to be 50

Fill in the missing word.

We should only use _________ to describe probability if we are directly told to in the question.

Winning the lottery

A child eating cereal for breakfast tomorrow

You will live to be 50

• Question 1

Match the situation with the word you would use to describe the chance of it happening.

## Column B

You will watch some telly tonight
likely
You will live to be 100
unlikely
Christmas day will be oon the 25t...
Certain
A new born baby will be a boy
Evens
EDDIE SAYS
You have to remember that this question is not actually talking about you, it's talking about a general person. I frequently get 'I watch telly every night so it's certain'. Not quite, it's likely but there are a number of ways you could end up not watching telly so it's nor certain.
• Question 2

What word would you use to describe...

The chance of you having a english lesson today.

Likely
EDDIE SAYS
Do you have to have an English lesson every day? What about Saturday and Sunday?
• Question 3

What word would you use to describe...

Picking a card out of a deck of cards and getting a red card

evens
EDDIE SAYS
A deck of cards has exactly 26 red cards and 26 black cards so it's exactly half that are red. This gives an even chance
• Question 4

What word would you use to describe the chance of picking a red ball out of a bag containing only red balls.

certain
EDDIE SAYS
If there's only red balls in there, you have to pull out a red ball.
• Question 5

Which of these two events is more likely

Event A: Rolling a normal dice and getting a number less than 7.

Event B: Rolling a normal dice and getting an odd number.

Event A
EDDIE SAYS
Event A has to happen as the numbers go up to 6. You can\'t have anything that is more likely to happen than certain, so this one has to be the more likely one.
• Question 6

Which of these two events is less likely

I have a bag with 7 red balls and 3 black balls

Event A: Pulling out a black ball

Event B: Pulling out a yellow ball

Event B
EDDIE SAYS
Event B can't happen (there aren't any yellow balls in the bag) so this one has to be the least likely.
• Question 7

Is it an even chance that it will rain tomorrow?

No
EDDIE SAYS
This is a really common mistake. There are only two things that could happen but they aren't equally likely to happen so it isn't an even chance.
• Question 8

Does the probability word correctly describe the situation.

EDDIE SAYS
These words are all valid. The one students get wrong is the first one. They say a coin could land on its edge so it cant be impossible. Yes and No, Theoretically a coin could land on its edge but the chance is so incredibly low we can ignore it (have you ever seen it happen?)
• Question 9

Which of these events are likely?

A child eating cereal for breakfast tomorrow
You will live to be 50
EDDIE SAYS
The only one here is that it isn\'t likely for you to win the lottery (if we ignore the fact you\'re probably too young to play it). The other two are likely events.
• Question 10

Fill in the missing word.

We should only use _________ to describe probability if we are directly told to in the question.

EDDIE SAYS
This is a key fact. Most probability is described using a number so you should only use words if the question says to.
---- OR ----

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