Table of Contents▾
Venn diagrams look easy until the question stops asking you to fill one in and starts asking you to read one. These eleven questions build from a two-set diagram with an unknown in it, through shading, set notation and three-set problems, up to a quadratic Venn and a probability without replacement. Each one has a complete worked solution and mark scheme, so you can see exactly how every mark is earned.
What are Venn diagrams?
A Venn diagram uses overlapping circles to show how sets of things are related. Each circle is a set, the overlap is what the sets have in common, and the rectangle around them is the universal set, written as ξ, which holds everything being considered. The numbers written inside the regions usually tell you how many things are in each region, not what those things are. The notation is where most marks are lost: A ∩ B means A and B, so it is the overlap; A ∪ B means A or B, so it is everything inside either circle; and A′ means not A, so it is everything outside circle A. Brackets matter too, because (A ∪ B) ∩ C and A ∪ (B ∩ C) are different regions. At GCSE and IGCSE, Venn diagrams are used to complete a diagram from given totals, to read off probabilities including conditional probabilities, to shade a region from its set notation, and to find the highest common factor and lowest common multiple from prime factors.
How to use this page
Try each question on paper first
Give yourself a real attempt before looking at the solution, because that is where the learning happens.
Check the calculator icon
A crossed-out calculator means non-calculator; a plain calculator means a calculator is allowed.
Reveal the worked solution
Open the solution under each question and compare it with your own method, step by step.
Read the mark scheme
See exactly where each method mark (M1) and accuracy mark (A1) is awarded, and remember that a completely correct Venn diagram is often worth several marks on its own.
Come back and redo it
Repeat any question you got wrong a few days later to lock the method in.
11 questions with full worked solutions and mark schemes - free PDF
Practice questions
Work through each question, then open the worked solution to check your method. The questions get harder as you go, from Grade 6 up to Grade 9.
Question 1, Grade 6, Non-calculator
A garden centre recorded what its customers bought one Saturday morning.
is the set of all customers that morning.
is the set of customers who bought seeds.
is the set of customers who bought compost.
The Venn diagram shows the number of customers in each region.
(a) Given that , find the value of . [2 marks]
(b) Find . [2 marks]
(c) One of the customers is chosen at random. Find . Give your answer as a fraction in its simplest form. [2 marks]
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Question 1 - Exam Solution
- The four regions of a two-set Venn diagram account for every element, so add all four and set the total equal to . That gives one equation in .
- Solve it, then substitute back to turn every region into a number.
- For the union, add the three regions the circles cover. For the probability, put the overlap over , not over the union.
| Step | Mark | Description | Got it? |
|---|---|---|---|
| M1 | Method - all four regions add to n(ξ) | ✓ | |
| A1 | Accuracy - correct value of x | ✓ |
Full marks: 2/2
| Step | Mark | Description | Got it? |
|---|---|---|---|
| Substitute to get 21, 15 and 8 | M1 | Method - evaluate the three regions | ✓ |
| A1 | Accuracy - correct union | ✓ |
Full marks: 2/2
| Step | Mark | Description | Got it? |
|---|---|---|---|
| , or the fraction | M1 | Method - correct numerator over n(ξ) | ✓ |
| A1 | Accuracy - simplified fraction | ✓ |
Full marks: 2/2
Question 2, Grade 6, Non-calculator
is the set of integers from 1 to 30.
Set is made up of the numbers generated by the sequence , where is a positive integer.
Set is made up of the numbers generated by the sequence , where is a positive integer.
(a) List the elements of set and the elements of set . [2 marks]
(b) Complete the Venn diagram to show the number of elements in each region.
[3 marks]
(c) Complete each statement using one of the symbols , , or .
(i)
(ii) [2 marks]
(d) A number is chosen at random from . Find . [1 mark]
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Question 2 - Exam Solution
- Substitute into each rule and stop as soon as the value goes past 30.
- Compare the two lists to find the elements in both. Every other element of goes in only, and every other element of goes in only.
- The outside region is everything in that is in neither list, so count it by subtraction.
| Step | Mark | Description | Got it? |
|---|---|---|---|
| B1 | Accuracy - correct set A, stopping at 30 | ✓ | |
| B1 | Accuracy - correct set B, stopping at 30 | ✓ |
Full marks: 2/2
| Step | Mark | Description | Got it? |
|---|---|---|---|
| , so 2 in the overlap | M1 | Method - identifies the shared elements | ✓ |
| M1 | Method - subtracts from n(ξ) to get the outside | ✓ | |
| A completely correct Venn diagram | A1 | Accuracy - all four regions correct and correctly placed | ✓ |
Full marks: 3/3
| Step | Mark | Description | Got it? |
|---|---|---|---|
| B1 | Accuracy - element symbol, and 18 is in both sets | ✓ | |
| B1 | Accuracy - subset symbol negated, because 8 is not in B | ✓ |
Full marks: 2/2
| Step | Mark | Description | Got it? |
|---|---|---|---|
| B1 | Accuracy - correct probability, simplified | ✓ |
Full marks: 1/1
Question 3, Grade 7, Non-calculator
Each member of a hillwalking club was asked which of these three items they had with them.
is the set of all the members.
is the set of members who had a map.
is the set of members who had a compass.
is the set of members who had a whistle.
(a) Describe, in words, what each of the shaded areas represents.
(i)
(ii)
(iii)
[3 marks]
(b) Write each of the three shaded regions in part (a) using set notation. [3 marks]
(c) Shade each Venn diagram to show:
(i) the members who had a compass only
(ii) all the members who had a whistle
(iii) the members who had exactly two of the three items
[3 marks]
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Question 3 - Exam Solution
- Read a shaded region one circle at a time: is the shading inside this circle, or outside it? Do that for all three.
- Then translate: inside is the set, outside is the complement, and "and" between them is .
- To shade, do the reverse. Work out which regions the description covers, then shade all of them and only them.
| Step | Mark | Description | Got it? |
|---|---|---|---|
| (i) map only, not compass and not whistle | B1 | Accuracy - identifies all three conditions | ✓ |
| (ii) none of the three items | B1 | Accuracy - recognises the region outside every circle | ✓ |
| (iii) all three items | B1 | Accuracy - recognises the central region | ✓ |
Full marks: 3/3
| Step | Mark | Description | Got it? |
|---|---|---|---|
| B1 | Accuracy - correct notation for "in one, out of the other two" | ✓ | |
| B1 | Accuracy - the complement of the union | ✓ | |
| B1 | Accuracy - the triple intersection | ✓ |
Full marks: 3/3
| Step | Mark | Description | Got it? |
|---|---|---|---|
| Only the crescent shaded | B1 | Accuracy - "only" means one region, not the whole circle | ✓ |
| The whole circle shaded | B1 | Accuracy - "all" includes every overlap | ✓ |
| The three pairwise regions shaded, centre left clear | B1 | Accuracy - "exactly two" excludes the centre | ✓ |
Full marks: 3/3
Question 4, Grade 7, Non-calculator
A cafe's menu has 50 dishes.
is the set of all 50 dishes.
is the set of dishes that are vegetarian.
is the set of dishes that are gluten-free.
is the set of dishes that are served hot.
The Venn diagram shows the number of dishes in each region.
Find:
(a) [1 mark]
(b) [1 mark]
(c) [1 mark]
(d) [2 marks]
(e) [2 marks]
(f) Parts (d) and (e) use the same three sets and the same two symbols. Only the bracket has moved. Explain why the answers are different. [2 marks]
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Question 4 - Exam Solution
- means "and", so it is the overlap. means "or", so it is everything in either.
- Always add the regions, not the set totals. A set total already contains its overlaps, so adding two of them double-counts.
- Where there is a bracket, do the bracket first. The bracket decides which set is combined with which.
| Step | Mark | Description | Got it? |
|---|---|---|---|
| B1 | Accuracy - all four regions of V | ✓ |
Full marks: 1/1
| Step | Mark | Description | Got it? |
|---|---|---|---|
| B1 | Accuracy - includes the centre | ✓ |
Full marks: 1/1
| Step | Mark | Description | Got it? |
|---|---|---|---|
| B1 | Accuracy - correct union | ✓ |
Full marks: 1/1
| Step | Mark | Description | Got it? |
|---|---|---|---|
| Identifies the three regions 6, 3 and 4 | M1 | Method - bracket first, then intersect with H | ✓ |
| A1 | Accuracy | ✓ |
Full marks: 2/2
| Step | Mark | Description | Got it? |
|---|---|---|---|
| All of (22), plus the 4 in but not | M1 | Method - bracket first, then union with V | ✓ |
| A1 | Accuracy | ✓ |
Full marks: 2/2
| Step | Mark | Description | Got it? |
|---|---|---|---|
| States that in (d) everything must be in , but in (e) all of is included | B1 | Reason - identifies the set outside the bracket | ✓ |
| Links this to the two different shaded regions, or to | B1 | Reason - explains the consequence | ✓ |
Full marks: 2/2
Question 5, Grade 7, Non-calculator
(a) Write 168 and 180 as products of their prime factors. [2 marks]
(b) Complete the Venn diagram to show the prime factors of 168 and 180.
[2 marks]
(c) Use the Venn diagram to write down the highest common factor (HCF) of 168 and 180. [1 mark]
(d) Use the Venn diagram to work out the lowest common multiple (LCM) of 168 and 180. [2 marks]
(e) Show that . Explain, using the Venn diagram, why this will always be true for any two numbers. [3 marks]
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Question 5 - Exam Solution
- Break each number down into primes and list every copy of each prime.
- A prime goes in the middle once for each copy the two numbers share. Any copies left over stay on their own side. Getting this wrong is where the marks go.
- The HCF is the middle. The LCM is everything.
| Step | Mark | Description | Got it? |
|---|---|---|---|
| B1 | Accuracy | ✓ | |
| B1 | Accuracy | ✓ |
Full marks: 2/2
| Step | Mark | Description | Got it? |
|---|---|---|---|
| Middle | M1 | Method - matches the number of copies, not just the primes | ✓ |
| 168 only and 180 only | A1 | Accuracy - all three regions correct | ✓ |
Full marks: 2/2
| Step | Mark | Description | Got it? |
|---|---|---|---|
| B1 | Accuracy - the product of the middle region | ✓ |
Full marks: 1/1
| Step | Mark | Description | Got it? |
|---|---|---|---|
| Multiplies all three regions together, using the middle once | M1 | Method | ✓ |
| A1 | Accuracy | ✓ |
Full marks: 2/2
| Step | Mark | Description | Got it? |
|---|---|---|---|
| B1 | Accuracy - the calculation | ✓ | |
| Writes and from the diagram | M1 | Method - names the regions | ✓ |
| A1 | Reason - the middle is counted once for each number | ✓ |
Full marks: 3/3
Question 6, Grade 8, Calculator allowed
A borough council estimates that, for a randomly chosen household in the borough:
- the probability that the household recycles glass is 0.45
- the probability that the household recycles food waste is 0.58
- the probability that the household recycles both is 0.31
(a) Find the probability that a randomly chosen household recycles neither glass nor food waste. [2 marks]
(b) There are 2000 households in the borough. Complete the Venn diagram to show the expected number of households that recycle glass only, food waste only, both, and neither.
[3 marks]
(c) A household is chosen at random. Find the probability that it recycles glass, given that it does not recycle food waste. Give your answer as a fraction in its simplest form. [2 marks]
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Question 6 - Exam Solution
- For (a), use the addition rule to find , then take the complement.
- For (b), subtract the overlap from each set total to get the "only" regions, then multiply every region probability by 2000.
- For (c), the condition restricts the sample space to the households outside . That restricted total becomes the denominator.
| Step | Mark | Description | Got it? |
|---|---|---|---|
| M1 | Method - the addition rule, subtracting the overlap | ✓ | |
| A1 | Accuracy - correct probability | ✓ |
Full marks: 2/2
| Step | Mark | Description | Got it? |
|---|---|---|---|
| and | M1 | Method - subtract the overlap from each set total | ✓ |
| Multiply each region probability by 2000 | M1 | Method - scale to expected frequencies | ✓ |
| A completely correct Venn diagram | A1 | Accuracy - all four values correct and correctly placed | ✓ |
Full marks: 3/3
| Step | Mark | Description | Got it? |
|---|---|---|---|
| M1 | Method - correct denominator (the restricted sample space) | ✓ | |
| A1 | Accuracy - correct simplified fraction | ✓ |
Full marks: 2/2
Question 7, Grade 8, Non-calculator
A bookshop surveys its stock. Every book is either a hardback or a paperback.
is the set of all the books in the shop.
is the set of books that are hardbacks.
is the set of books that are fiction.
The Venn diagram shows the percentage of the shop's books in each region.
(a) Find the probability that a randomly chosen book is a paperback, given that it is fiction. Give your answer as a fraction in its simplest form. [2 marks]
(b) The shop has 800 books in total. By working out the number of fiction books and the number of paperback fiction books, show that your answer to part (a) is unchanged. [3 marks]
(c) A customer claims that the probability a book is fiction, given that it is a paperback, must also equal the answer to part (a), because it involves the same two categories.
Show that the customer is wrong, and find the correct probability. [3 marks]
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Question 7 - Exam Solution
- The percentages already behave like counts out of 100, so they can be used directly.
- A condition shrinks the sample space. For (a) the denominator is the fiction total, not 100.
- For (b), scale every region by 800 and repeat. For (c), the condition changes, so the denominator changes.
| Step | Mark | Description | Got it? |
|---|---|---|---|
| M1 | Method - correct denominator (the restricted sample space) | ✓ | |
| A1 | Accuracy - correct simplified fraction | ✓ |
Full marks: 2/2
| Step | Mark | Description | Got it? |
|---|---|---|---|
| M1 | Method - convert a percentage region to a number of books | ✓ | |
| M1 | Method - correct denominator in the new scale | ✓ | |
| , unchanged | A1 | Accuracy - shows the probability is the same | ✓ |
Full marks: 3/3
| Step | Mark | Description | Got it? |
|---|---|---|---|
| M1 | Method - correct denominator for the new condition | ✓ | |
| A1 | Accuracy - correct simplified fraction | ✓ | |
| States , so the customer is wrong | A1 | Reason - the two conditionals are not equal | ✓ |
Full marks: 3/3
Question 8, Grade 8, Non-calculator
A leisure centre has 200 members. Every member uses at least one of the swimming pool, the gym and the tennis courts.
is the set of all 200 members.
is the set of members who use the swimming pool.
is the set of members who use the gym.
is the set of members who use the tennis courts.
92 members use the gym. Of these, 32 also use the tennis courts.
96 members use the swimming pool. Of these, 28 also use the gym and 20 also use the tennis courts.
12 members use all three facilities.
(a) Complete the Venn diagram to show this information.
[3 marks]
(b) Find and . [2 marks]
(c) One member is chosen at random. Find . [1 mark]
(d) Given that a member uses the tennis courts, find the probability that this member also uses the swimming pool. Give your answer as a fraction in its simplest form. [2 marks]
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Question 8 - Exam Solution
- Always fill a three-set Venn from the centre outwards. Start with the region in all three sets, then the pairwise-only regions, then the single-set regions, then whatever is left over.
- "Of these" always means an overlap that already contains the centre, so subtract the centre from it.
- Since every member uses at least one facility, the region outside all three circles is 0.
| Step | Mark | Description | Got it? |
|---|---|---|---|
| Centre 12, then the pairwise-only regions 20, 16 and 8 | M1 | Method - subtract the centre from each pairwise overlap | ✓ |
| only and only | M1 | Method - subtract the placed regions from each set total | ✓ |
| A completely correct Venn diagram, including only | A1 | Accuracy - all seven regions correct and correctly placed | ✓ |
Full marks: 3/3
| Step | Mark | Description | Got it? |
|---|---|---|---|
| B1 | Accuracy - correct region identified and read off | ✓ | |
| B1 | Accuracy - recognises that nobody sits outside all three | ✓ |
Full marks: 2/2
| Step | Mark | Description | Got it? |
|---|---|---|---|
| B1 | Accuracy - correct probability, simplified | ✓ |
Full marks: 1/1
| Step | Mark | Description | Got it? |
|---|---|---|---|
| M1 | Method - correct denominator, read off the Venn | ✓ | |
| A1 | Accuracy - correct simplified fraction | ✓ |
Full marks: 2/2
Question 9, Grade 8, Non-calculator
A museum recorded which galleries its visitors saw one Saturday.
is the set of all the visitors that day.
is the set of visitors who saw the Roman gallery.
is the set of visitors who saw the wildlife gallery.
(a) Find the ratio of visitors who saw the Roman gallery to the total number of visitors. Give your answer in its simplest form. [2 marks]
(b) A visitor is chosen at random. Find the probability that they saw the wildlife gallery, given that they saw the Roman gallery. [2 marks]
(c) A visitor is chosen at random. Find the probability that they saw the Roman gallery, given that they saw exactly one gallery. [2 marks]
(d) Find , and explain why this is not the number of visitors who saw exactly one gallery. [2 marks]
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Question 9 - Exam Solution
- Read and off the diagram, then cancel the ratio down.
- Every conditional restricts the sample space. For (b) the condition is a named set, so the denominator is .
- For (c) the condition is not a named set. "Exactly one" has to be built: it is the two crescent regions, and it excludes both the overlap and the outside.
| Step | Mark | Description | Got it? |
|---|---|---|---|
| and , giving | M1 | Method - correct ratio before cancelling | ✓ |
| A1 | Accuracy - fully simplified | ✓ |
Full marks: 2/2
| Step | Mark | Description | Got it? |
|---|---|---|---|
| M1 | Method - correct numerator over the correct denominator | ✓ | |
| A1 | Accuracy - simplified fraction | ✓ |
Full marks: 2/2
| Step | Mark | Description | Got it? |
|---|---|---|---|
| Denominator | M1 | Method - builds "exactly one" and excludes both the overlap and the outside | ✓ |
| A1 | Accuracy - simplified fraction | ✓ |
Full marks: 2/2
| Step | Mark | Description | Got it? |
|---|---|---|---|
| B1 | Accuracy - correct union | ✓ | |
| Explains that the union includes the 42 who saw both, while "exactly one" excludes them | B1 | Reason - the distinction between at least one and exactly one | ✓ |
Full marks: 2/2
Question 10, Grade 8, Non-calculator
A community allotment has 120 plot holders. Every plot holder grows at least one of potatoes, tomatoes and beans.
is the set of all 120 plot holders.
is the set of plot holders who grow potatoes.
is the set of plot holders who grow tomatoes.
is the set of plot holders who grow beans.
Three fifths of the plot holders grow exactly one crop.
5% of the plot holders grow all three crops.
20 plot holders grow potatoes and tomatoes.
22 plot holders grow tomatoes and beans.
62 plot holders grow potatoes.
58 plot holders grow beans.
(a) Complete the Venn diagram to show this information.
[5 marks]
(b) Find the number of plot holders who grow tomatoes. [1 mark]
(c) A plot holder is chosen at random. Find the probability that they grow potatoes, given that they grow at least two crops. Give your answer as a fraction in its simplest form. [2 marks]
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Question 10 - Exam Solution
- Start at the centre, then use each "and" figure to fill a pairwise region.
- One region cannot be reached that way. The clue "three fifths grow exactly one crop" is the way in: if 72 grow exactly one, the other 48 grow at least two, and those 48 are precisely the four overlap regions.
- Then use and for two of the singles, and subtract from 120 for the last.
| Step | Mark | Description | Got it? |
|---|---|---|---|
| M1 | Method - a percentage of the total gives the centre | ✓ | |
| only and only | M1 | Method - subtract the centre from each pairwise overlap | ✓ |
| "at least two" , so only | M1 | Method - uses the "exactly one" clue to reach the fourth overlap | ✓ |
| only and only | M1 | Method - subtract the placed regions from each set total | ✓ |
| A completely correct Venn diagram, including only | A1 | Accuracy - all seven regions correct and correctly placed | ✓ |
Full marks: 5/5
| Step | Mark | Description | Got it? |
|---|---|---|---|
| B1 | Accuracy - correct total read off the completed Venn | ✓ |
Full marks: 1/1
| Step | Mark | Description | Got it? |
|---|---|---|---|
| Denominator , numerator | M1 | Method - correct four-region denominator and three-region numerator | ✓ |
| A1 | Accuracy - simplified fraction | ✓ |
Full marks: 2/2
Question 11, Grade 9, Calculator allowed
A school orchestra has 55 members.
is the set of all 55 members.
is the set of members who play the violin.
is the set of members who play the cello.
(a) Show that . [3 marks]
(b) Solve the equation to find the value of , and write down the number of members in each region of the Venn diagram. [3 marks]
(c) Two different members of the orchestra are chosen at random. Find the probability that they both play the violin. [3 marks]
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Question 11 - Exam Solution
- The four regions fill the universal set, so add them and set the total equal to 55. Because one region is a product, this gives a quadratic, not a linear equation.
- A quadratic has two roots. Only one can be a number of people, so test both against the diagram.
- The two members are different, so the second is chosen from what is left. This is without replacement.
| Step | Mark | Description | Got it? |
|---|---|---|---|
| M1 | Method - all four regions add to n(ξ) | ✓ | |
| M1 | Method - expands and collects correctly | ✓ | |
| A1 | Accuracy - reaches the required form | ✓ |
Full marks: 3/3
| Step | Mark | Description | Got it? |
|---|---|---|---|
| M1 | Method - correct factorisation | ✓ | |
| , rejecting with a reason | A1 | Accuracy - correct root, correctly justified | ✓ |
| Regions 36, 4, 10 and 5 | A1 | Accuracy - all four regions correct | ✓ |
Full marks: 3/3
| Step | Mark | Description | Got it? |
|---|---|---|---|
| M1 | Method - correct number of violinists | ✓ | |
| M1 | Method - without replacement, both numerator and denominator reduced by one | ✓ | |
| A1 | Accuracy - correct simplified fraction | ✓ |
Full marks: 3/3
Print it, work offline, mark yourself against the scheme.
Frequently Asked Questions
A Venn diagram uses overlapping circles to show how sets of things are related. Each circle is a set, the overlap is what the sets have in common, and the rectangle around them is the universal set, which holds everything being considered. The numbers inside the regions usually tell you how many items are in each region, not what those items are. Venn diagrams appear on both GCSE and IGCSE papers, most often in probability questions.
The intersection symbol ∩ means "and", so A ∩ B is the overlap of the two circles. The union symbol ∪ means "or", so A ∪ B is everything inside either circle, including the overlap. A prime after a set, written A′, means the complement, or "not", so A′ is everything outside circle A. Brackets matter: (A ∪ B) ∩ C is not the same region as A ∪ (B ∩ C), and the two usually give different answers.
Always work from the centre outwards. Start with the number in all three sets, because every other overlap contains it. Then fill each pairwise overlap by subtracting the centre from the "and" figure you are given. Then fill each single-set region by subtracting everything already placed from that set's total. Whatever is left over goes in the last region, or outside the circles.
A condition shrinks the sample space. "Given that" tells you which region to use as the denominator, and it is almost never the whole universal set. The probability of A given B is the number in A ∩ B divided by the number in B, not by the total. If the condition is not a named set, such as "given that they chose exactly one", you have to build that region from the diagram yourself before you can use it.
Write each number as a product of its prime factors, then put the shared factors in the overlap and the rest in the outer regions. Count the copies: if one number has three 2s and the other has two, then two 2s go in the middle and one stays outside. The HCF is the product of the overlap, and the LCM is the product of everything in the diagram.
Venn diagrams appear on both tiers. Foundation questions usually ask you to complete a diagram and read a simple probability from it. Higher questions go further: conditional probability, three-set problems, algebraic regions and probability without replacement. This page is aimed at the Higher tier work, from Grade 6 up to Grade 9.
Keep revising
Once you are confident with Venn diagrams, browse the full topic lists for GCSE Maths topics and IGCSE Maths topics, and check the GCSE grade boundaries and IGCSE grade boundaries to set your target. For more exam-style practice, try the Circle Theorems Practice Questions and the Simultaneous Equations Practice Questions.
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