Q1
Not Answered
NATIVE
Q1. A fair die is rolled once. What is the probability of getting a prime number?
Prime outcomes are 2, 3, 5 (3 outcomes) out of 6. Probability = 3/6 = 1/2.
Home / General Aptitude / Probability
General Aptitude
Probability
Probability aptitude questions on dice, cards, and selection-based problem sets with step-by-step explanations and instant answer checks.
About Probability
Probability measures the likelihood of an event occurring, expressed as a number between 0 (impossible) and 1 (certain). In aptitude tests, probability questions typically involve dice rolls, card draws from a standard deck of 52 cards, coin tosses, or selection from a group of items. The basic formula is P(Event) = Number of favorable outcomes ÷ Total number of possible outcomes. Key concepts include independent events (the outcome of one does not affect another), mutually exclusive events, and conditional probability. Below are solved probability questions covering these essential patterns.
Key Takeaways
- Total outcomes for N coin tosses = 2^N. For N dice = 6^N.
- Cards: 52 total = 4 suits × 13 ranks. Know the composition of the deck.
- For 'or' events: P(A or B) = P(A) + P(B) - P(A and B).
Frequently Asked Questions
What is the basic formula for probability?
Probability = Number of favorable outcomes ÷ Total number of possible outcomes. Always express as a fraction, decimal, or percentage between 0 and 1.
What are independent and mutually exclusive events?
Independent: Outcome of one does NOT affect the other (e.g., rolling dice twice). P(A and B) = P(A) × P(B). Mutually exclusive: Events cannot occur together (e.g., getting heads and tails on one coin toss). P(A or B) = P(A) + P(B).
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Q2
Not Answered
NATIVE
Q2. A fair die is rolled once. What is the probability of getting an even number?
Even outcomes are 2, 4, 6 (3 outcomes) out of 6. Probability = 3/6 = 1/2.
Q3
Not Answered
NATIVE
Q3. A fair die is rolled once. Probability of getting a number greater than 3?
Numbers greater than 3: 3 outcomes out of 6. Probability = 3/6.
Q4
Not Answered
NATIVE
Q4. A bag has 1 red and 7 blue balls. Probability of picking a red ball?
Favorable outcomes = 1, total outcomes = 8. So probability = 1/8.
Q5
Not Answered
NATIVE
Q5. A fair die is rolled once. Probability of getting a number greater than 2?
Numbers greater than 2: 4 outcomes out of 6. Probability = 4/6.
Q6
Not Answered
NATIVE
Q6. A fair die is thrown once. What is the probability of getting 1?
Only one favorable outcome (1) out of 6 outcomes. Probability = 1/6.
Q7
Not Answered
NATIVE
Q7. A bag has 6 red and 6 blue balls. Probability of picking a red ball?
Favorable outcomes = 6, total outcomes = 12. So probability = 6/12.
Q8
Not Answered
NATIVE
Q8. A fair die is thrown once. What is the probability of getting 4?
Only one favorable outcome (4) out of 6 outcomes. Probability = 1/6.
Q9
Not Answered
NATIVE
Q9. A bag has 4 red and 8 blue balls. Probability of picking a red ball?
Favorable outcomes = 4, total outcomes = 12. So probability = 4/12.
Q10
Not Answered
NATIVE
Q10. From a standard 52-card deck, what is the probability of drawing a red card?
Red suits are hearts and diamonds: 13 + 13 = 26 cards. Probability = 26/52 = 1/2.
Q11
Not Answered
NATIVE
Q11. A bag has 4 red and 5 blue balls. Probability of picking a red ball?
Favorable outcomes = 4, total outcomes = 9. So probability = 4/9.
Q12
Not Answered
NATIVE
Q12. From a standard 52-card deck, what is the probability of drawing a Spade?
There are 13 spades in 52 cards. Probability = 13/52 = 1/4.
Q13
Not Answered
NATIVE
Q13. From a standard 52-card deck, what is the probability of drawing a Diamond?
There are 13 diamonds in 52 cards. Probability = 13/52 = 1/4.
Q14
Not Answered
NATIVE
Q14. From a standard 52-card deck, what is the probability of drawing a Club?
There are 13 clubs in 52 cards. Probability = 13/52 = 1/4.
Q15
Not Answered
NATIVE
Q15. A bag has 2 red and 2 blue balls. Probability of picking a red ball?
Favorable outcomes = 2, total outcomes = 4. So probability = 2/4.
Q16
Not Answered
NATIVE
Q16. From a standard 52-card deck, what is the probability of drawing a Heart?
There are 13 hearts in 52 cards. Probability = 13/52 = 1/4.
Q17
Not Answered
NATIVE
Q17. From a standard 52-card deck, what is the probability of drawing a black card?
Black suits are spades and clubs: 13 + 13 = 26 cards. Probability = 26/52 = 1/2.
Q18
Not Answered
NATIVE
Q18. A bag has 1 red and 3 blue balls. Probability of picking a red ball?
Favorable outcomes = 1, total outcomes = 4. So probability = 1/4.
Q19
Not Answered
NATIVE
Q19. From a 52-card deck, what is the probability of drawing a face card (J, Q, or K)?
Each suit has J, Q, K so face cards = 3 x 4 = 12. Probability = 12/52 = 3/13.
Q20
Not Answered
NATIVE
Q20. A bag has 1 red and 8 blue balls. Probability of picking a red ball?
Favorable outcomes = 1, total outcomes = 9. So probability = 1/9.
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Probability Formula, shortcuts & preparation guide
Master probability with regular practice. Key topics include percentage calculations, profit/loss, ratio, and time-work problems. Use shortcut methods for quick calculations and practice 15-20 questions daily to build speed and accuracy. This topic frequently appears in placement aptitude rounds.
Key formulas
- Regular practice improves accuracy
Probability Practice Questions with Answers
Build speed and accuracy with curated probability practice. Each quiz includes solved explanations, timed mode, and instant correctness feedback.
How to prepare effectively for this topic?
Practice short timed sets daily, review every explanation, and track recurring mistakes for weekly revision.
Are these questions useful for placements and competitive exams?
Yes. The format mirrors common screening rounds with option-based answers and explanation-driven learning.