ProbabilityTrivia Questions & Answers
8 probability trivia questions, each with the correct answer and a short explanation.
🧠 Play today’s Daily IQ Challenge →Probability Quiz — 8 Questions
Each question reveals the answer and a quick explanation below it.
1. A box has 4 red and 6 blue balls. Chance of drawing a red ball?
Answer: 2/5. 4 red out of 10 total equals 4/10, which simplifies to 2/5.
2. If you flip a fair coin twice, chance of two heads?
Answer: 1/4. Each flip has 1/2 chance, so two heads is 1/2 x 1/2 = 1/4.
3. Two fair coins are flipped. Given at least one is heads, what is the chance both are heads?
Answer: 1 in 3. Of the three outcomes with a head (HT, TH, HH), only HH has both, giving 1 in 3.
4. Two fair dice are rolled. What is the probability the two numbers sum to 7?
Answer: 1/6. Six of the 36 equally likely outcomes total 7, and 6/36 simplifies to 1/6.
5. A bag holds 3 red and 2 black balls. You draw two without replacing. P(both red)?
Answer: 3/10. It is 3/5 times 2/4 = 6/20, which simplifies to 3/10.
6. Three people are asked their birth weekday. Probability all three differ?
Answer: 30/49. It is 7/7 x 6/7 x 5/7 = 210/343, which simplifies to 30/49.
7. A die is rolled twice. What is the probability of getting at least one six?
Answer: 11/36. The chance of no six is (5/6) squared = 25/36, so at least one six is 11/36.
8. In a room of 23 strangers, what is approximately the probability two share a birthday? ~50%. With 70 strangers it is ~99.9%. What is the NAME of this counterintuitive result?
Answer: Birthday Paradox. The Birthday Paradox (or Birthday Problem) describes how surprisingly few people are needed for a shared-birthday probability to exceed 50%.
More IQ & Logic quizzes
Ready to prove your rank?
Take today’s Daily IQ Challenge — 12 fresh questions, one global leaderboard, a new test every day.
🧠 Play today’s Daily IQ Challenge →