Sets: JAMB Mathematics Questions, Answers & Notes

What Sets covers in the JAMB Mathematics syllabus

A set is a collection of distinct objects. The union (A∪B) gathers all elements in either set; the intersection (A∩B) keeps only common elements; the complement A' contains everything in the universal set U that is not in A. For two sets, n(A∪B) = n(A) + n(B) − n(A∩B) — a formula that solves most 'how many' word problems, often with a Venn diagram. A set of n elements has 2ⁿ subsets (2ⁿ − 1 proper subsets). Disjoint sets share nothing, so their intersection is the empty set { }.

For Sets, JAMB expects you to be able to:

• Perform union, intersection and complement operations on sets
• Use the formula n(A∪B) = n(A)+n(B)−n(A∩B) to solve word problems
• Identify subsets, the empty set and the number of subsets of a set

Key facts & revision notes: Sets

These are the recurring points our Sets questions test — revise them until each feels automatic, then practise the questions above to lock them in.

• The intersection A ∩ B contains only the elements common to both sets: 3 and 4.
• The union A ∪ B contains every element in either set, listed once: {a, b, c, d}.
• A set with n elements has 2ⁿ subsets.
• n(A ∪ B) = n(A) + n(B) − n(A ∩ B) = 20 + 15 − 8 = 27.
• Prime numbers have exactly two factors.
• Below 10 these are 2, 3, 5 and 7 (1 is not prime).
• The complement A' contains the elements of U that are not in A: {1, 3, 5}.
• The empty set contains no elements and is written { } or ∅.
• {0} contains one element (0).
• Since A is a subset of B, A ∩ B = A.
• Elements in B only = n(B) − n(A) = 9 − 5 = 4.
• Offering at least one = 25 + 20 − 10 = 35.
• The integers from 1 to 5 inclusive are 1, 2, 3, 4 and 5.
• From n(A ∪ B) = n(A) + n(B) − n(A ∩ B): 30 = 18 + 17 − n(A ∩ B), so n(A ∩ B) = 35 − 30 = 5.
• The symbol ∈ means 'is an element of'.
• ⊆ means 'is a subset of', ∪ union, ∩ intersection.
• Every element of B (4 and 8) is in A, so B is a subset of A: B ⊆ A.
• A set of 3 elements has 2³ = 8 subsets.
• Proper subsets exclude the set itself: 8 − 1 = 7.
• Disjoint sets have no common elements, so their intersection is the empty set { }.
• Like at least one = 50 − 5 = 45.
• Both = n(tea) + n(coffee) − (at least one) = 30 + 25 − 45 = 10.
• Even numbers: 2,4,6,8,10.
• Common to both within U: 6.

Worked examples

Three Sets questions with the answer and a short explanation, so you can see how the topic is set before you practise the full set.

How Sets is tested in JAMB Mathematics

Our Sets bank holds 40 questions (15 easy, 21 medium, 4 hard). JAMB Mathematics typically returns to Sets year after year, so steady practice on this topic is high-value revision. Questions are multiple-choice with four options, and at UTME pace you get roughly 40 seconds each — which is why timed practice matters.

How to answer Sets questions

Work the stem first and predict the answer before you look at the options; then eliminate the ones that contradict the key facts above. Watch for “which is not…”, “all of the above” and “except” style stems, which are where rushed candidates lose easy marks on Sets. If a calculation or a precise definition is involved, work it from first principles rather than guessing from a half-remembered rule. When two options look right, re-read the stem for the qualifier that separates them — JAMB rarely repeats an option by accident. If you are still unsure, eliminate the two weakest choices to lift your odds, flag the question, and move on; never burn a full minute on one Mathematics item when the exam gives you about forty seconds each. Then come back to flagged questions with whatever time remains. The single most reliable way to get faster at Sets is repeated timed practice, so use the button above until the recurring patterns feel automatic.

Common mistakes to avoid in Sets

The errors that cost marks on Sets are usually careless rather than conceptual: misreading a negative stem, confusing two similar terms, or rushing a definition you actually know. Candidates also over-rely on “expo” and last-minute cramming instead of understanding the topic — which fails the moment JAMB rephrases a familiar idea. Treat every option as a claim to be checked against the facts above, keep your working tidy for any calculation, and don’t change a considered answer on a hunch. Above all, revise Sets actively by answering questions, not just by re-reading notes — recall under time is what the exam rewards.

Frequently asked questions

Is Sets part of the JAMB Mathematics syllabus?

Yes. Sets is a recognised topic in the JAMB Mathematics syllabus, covering perform union, intersection and complement operations on sets. You should be able to recall its key facts and apply them to multiple-choice questions.

How many Sets questions can I practise on Belmadeng?

There are 40 original, JAMB-standard Sets questions in our free bank, each with the correct answer and a worked explanation. You can practise them untimed or as a timed test.

What are the most important points to know about Sets?

A set is a collection of distinct objects. The union (A∪B) gathers all elements in either set; the intersection (A∩B) keeps only common elements; the complement A' contains everything in the universal set U that is not in A. For two sets, n(A∪B) = n(A) + n(B) − n(A∩B) — a formula that solves most 'h…

How do I answer Sets questions quickly in JAMB?

Read the stem carefully, eliminate clearly wrong options, and match the remaining choices to the key facts for Sets. Practising timed Sets questions builds the speed you need for UTME's pace of about 40 seconds per question.

Are these JAMB Mathematics Sets questions past questions or original?

They are original questions written to JAMB (UTME) standard and mapped to the official syllabus — not reproduced past papers. This keeps them legal to use freely while closely mirroring how the real exam tests the topic.

Where can I practise Sets questions free without signing up?

Right here — tap “Start Sets practice” on this page to begin instantly. Belmadeng's CBT practice is completely free and needs no sign-up, download or subscription.

About these questions: original, JAMB-standard items written from the official UTME Mathematics syllabus (last reviewed 2026-09-18). Belmadeng is an independent study platform and is not affiliated with JAMB. Spotted an error? Use the report link.