Syllabus Edition

First teaching 2021

Last exams 2024

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Basic Probability (CIE IGCSE Maths: Extended)

Exam Questions

2 hours38 questions
1
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2 marks

The probability that Kim wins a game is 0.72 .
In one year Kim will play 225 games.

Work out an estimate of the number of games Kim will win.

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2
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1 mark

Samira has a bag containing 20 sweets.
In the bag, there are 5 red, 6 green and 9 yellow sweets.

Samira chooses one sweet at random from the bag.

Write down the probability that she chooses a yellow sweet.

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3
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2 marks

The probability that a sweet made in a factory is the wrong shape is 0.0028.
One day, the factory makes 25 000 sweets.
 
Calculate the number of sweets that are expected to be the wrong shape.

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4
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1 mark

A box contains 3 blue pens, 4 red pens and 8 green pens only.
A pen is chosen at random from the box.

Find the probability that this pen is green.

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5
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2 marks

The probability that a biased dice will land on a five is 0.3

Megan is going to roll the dice 400 times.

Work out an estimate for the number of times the dice will land on a five.

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6a
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1 mark

Jane has a packet of seeds.
The probability that a seed will grow is 0.75

What is the probability that a seed will not grow?

6b
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2 marks

Jane plants 200 of these seeds.

Estimate the number of the seeds that will grow.

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1a
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2 marks

A bag contains blue, red, yellow and green balls only.
A ball is taken from the bag at random.
The table shows some information about the probabilities.

 Colour Blue Red Yellow Green
 Probability 0.15 0.2   0.43


Complete the table.

1b
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1 mark

Abdul takes a ball at random and replaces it in the bag.
He does this 200 times.

Find how many times he expects to take a red ball.

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2
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2 marks

Sofia has a bag containing 8 blue beads and 7 red beads only.
She takes one bead out of the bag at random and replaces it.
She does this 90 times.
 
Find the number of times she expects to take a red bead.

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3
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2 marks

A group of 200 people were asked which city they would like to visit next.
The table shows the results.

City London Paris New York Tokyo
Number of people 50 48 56 46

 
A person from the group is chosen at random.
 
Write down the probability that this person would like to visit either Paris or Tokyo next.

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4
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3 marks

One of the teachers at a school is chosen at random.

The probability that this teacher is female is  3 over 5

There are 36 male teachers at the school.

Work out the total number of teachers at the school.

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5a
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2 marks

There are only red counters, blue counters, white counters and black counters in a bag.

The table shows the probability that a counter taken at random from the bag will be red or blue.

Colour red blue white black
Probability 0.2 0.5    

The number of white counters in the bag is the same as the number of black counters in the bag.

Tania takes at random a counter from the bag.

Work out the probability that Tania takes a white counter.

5b
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2 marks

There are 240 counters in the bag.

Work out the number of red counters in the bag.

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6
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3 marks

Rhiana plays a game.

The probability that she will lose the game is 0.32
The probability that she will draw the game is 0.05

Rhiana is going to play the game 200 times.

Work out an estimate for the number of times Rhiana will win the game.

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1a
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2 marks

A bag contains 7 red discs, 5 green discs and 2 pink discs.

Helen takes one disc at random, records the colour and replaces it in the bag.
She does this 140 times.
 
Find how many times she expects to take a green disc.

1b
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2 marks

Helen adds 9 green discs and some pink discs to the discs already in the bag.
The probability of taking a green disc is now 2 over 7.
 
Find the number of pink discs that Helen added to the bag.

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2
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2 marks

Bill has some counters in a bag.

3 of the counters are red.
7 of the counters are blue.
The rest of the counters are yellow.

Bill takes at random a counter from the bag.

The probability that he takes a yellow counter is 2 over 7

How many yellow counters are in the bag before Bill takes a counter?

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3a
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2 marks

Karl wants to raise money for charity.
He designs a game for people to play.

Karl uses a fair 10-sided dice for the game.
The dice is numbered from 1 to 10

Each person will roll the dice once.
A person wins the game if the dice lands on a multiple of 4

Ali plays the game once.

Work out the probability that Ali will win the game.

3b
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3 marks

Each person pays 30p to play the game once.
The prize for a win is £1

Karl thinks that the game will be played 100 times.

Work out an estimate for how much money Karl will raise for charity.

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4
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3 marks

There are only blue counters, green counters, red counters and yellow counters in a bag.

Olga is going to take at random a counter from the bag.

The table shows the probability that Olga will take a blue counter and the probability that she will take a yellow counter.

Colour blue green red yellow
Probability 0.4     0.15


The number of red counters in the bag is 4 times the number of green counters in the bag.

Complete the table.

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5
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3 marks

There are only blue cubes, yellow cubes and green cubes in a bag.

There are

  twice as many blue cubes as yellow cubes
and  four times as many green cubes as blue cubes.


Hannah takes at random a cube from the bag.

Work out the probability that Hannah takes a yellow cube.

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6a
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1 mark

There are only blue counters, yellow counters, green counters and red counters in a bag.
A counter is taken at random from the bag.

The table shows the probabilities of getting a blue counter or a yellow counter or a green counter.

Colour blue yellow green red
Probability 0.2 0.35 0.4  


Work out the probability of getting a red counter.

6b
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2 marks

What is the least possible number of counters in the bag?
You must give a reason for your answer.

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7a
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4 marks

There are some counters in a bag.
The counters are red or white or blue or yellow.

Bob is going to take at random a counter from the bag.

The table shows each of the probabilities that the counter will be blue or will be yellow.

Colour red white blue yellow
Probability     0.45 0.25


There are 18 blue counters in the bag.

The probability that the counter Bob takes will be red is twice the probability that the counter will be white.

Work out the number of red counters in the bag.

7b
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1 mark

A marble is going to be taken at random from a box of marbles.
The probability that the marble will be silver is 0.5

There must be an even number of marbles in the box.

Explain why.

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