Probability: JAMB Mathematics Questions, Answers & Notes

What Probability covers in the JAMB Mathematics syllabus

Probability measures how likely an event is, on a scale from 0 (impossible) to 1 (certain). For equally likely outcomes, P(event) = (favourable outcomes) ÷ (total outcomes). The complement rule: P(not A) = 1 − P(A). For mutually exclusive events (can't both happen), P(A or B) = P(A) + P(B). For independent events (one doesn't affect the other), P(A and B) = P(A) × P(B). Typical contexts include coins, dice, cards and balls in a bag — count the favourable and total outcomes carefully.

For Probability, JAMB expects you to be able to:

• Calculate the probability of simple events
• Use the complement rule and the probability scale
• Apply the addition rule (mutually exclusive) and multiplication rule (independent events)

Key facts & revision notes: Probability

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

• There are 2 equally likely outcomes (H, T); P(head) = 1/2.
• There are 6 equally likely outcomes; P(4) = 1/6.
• An impossible event can never happen, so its probability is 0.
• A certain event always happens, so its probability is 1.
• P(red) = red/total = 3/(3+2) = 3/5.
• Even numbers 2,4,6 (3 outcomes) out of 6: P = 3/6 = 1/2.
• P(not A) = 1 − P(A) = 1 − 0.3 = 0.7.
• Numbers greater than 4 are 5 and 6 (2 outcomes): P = 2/6 = 1/3.
• Outcomes: HH, HT, TH, TT.
• 'MATHEMATICS' has 11 letters; vowels A, E, A, I = 4.
• For mutually exclusive events, P(A or B) = P(A) + P(B).
• For independent events, P(A and B) = P(A) × P(B).
• Multiples of 3: 3, 6, 9 (3 cards).
• P(black) = 6/(4+6) = 6/10 = 3/5.
• There are 6 ways to make 7 out of 36 outcomes: 6/36 = 1/6.
• All probabilities lie between 0 (impossible) and 1 (certain).
• Independent events: (1/6) × (1/6) = 1/36.
• P(not green) = P(yellow) = 5/10 = 1/2.
• Primes ≤ 20: 2,3,5,7,11,13,17,19 = 8 numbers.
• P(no rain) = 1 − 0.25 = 0.75.
• One favourable outcome out of six: 1/6.
• One of two equally likely outcomes: 1/2.
• Odd numbers {1,3,5}: 3/6 = 1/2.
• P(not A) = 1 − 0.4 = 0.6.

Worked examples

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

How Probability is tested in JAMB Mathematics

Our Probability bank holds 40 questions (16 easy, 17 medium, 7 hard). JAMB Mathematics typically returns to Probability 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 Probability 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 Probability. 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 Probability is repeated timed practice, so use the button above until the recurring patterns feel automatic.

Common mistakes to avoid in Probability

The errors that cost marks on Probability 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 Probability actively by answering questions, not just by re-reading notes — recall under time is what the exam rewards.

Frequently asked questions

Is Probability part of the JAMB Mathematics syllabus?

Yes. Probability is a recognised topic in the JAMB Mathematics syllabus, covering calculate the probability of simple events. You should be able to recall its key facts and apply them to multiple-choice questions.

How many Probability questions can I practise on Belmadeng?

There are 40 original, JAMB-standard Probability 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 Probability?

Probability measures how likely an event is, on a scale from 0 (impossible) to 1 (certain). For equally likely outcomes, P(event) = (favourable outcomes) ÷ (total outcomes). The complement rule: P(not A) = 1 − P(A). For mutually exclusive events (can't both happen), P(A or B) = P(A) + P(B). For inde…

How do I answer Probability questions quickly in JAMB?

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

Are these JAMB Mathematics Probability 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 Probability questions free without signing up?

Right here — tap “Start Probability 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.