Download Free PDF of Probability Exercise 13.3 NCERT Solutions for Class 12 Maths
FAQs on CBSE Class 12 Maths Chapter 13 Probability – NCERT Solutions Exercise 13.3 [2025-26]
1. How are NCERT Solutions for Class 12 Maths Chapter 13 Exercise 13.3 helpful in understanding conditional probability?
These NCERT Solutions provide stepwise explanations on applying conditional probability and related theorems to problems as per the latest CBSE syllabus. By focusing on the method of defining events, clearly outlining what is 'given', and using formulas like P(A|B) = P(A ∩ B)/P(B), students develop a clear and exam-ready approach to tricky probability concepts.
2. What type of step-by-step methods should I follow when solving NCERT Exercise 13.3 problems?
Begin with defining all relevant events (e.g., A and B). Then, identify any ‘given that’ condition for clarity. Apply the multiplication law or conditional probability formula as needed, always calculating denominators first in conditional questions. Box key results and clearly mention each calculated probability step.”
3. Which are the most common mistakes students make while solving conditional probability questions in Exercise 13.3?
- Mixing up formulas for independent and dependent events
- Forgetting to calculate the correct denominator in conditional probability
- Not defining events properly before solving
- Skipping calculation steps, leading to errors
Always check for ‘given that’ in the question and ensure all events and steps are well-defined in your solution.
4. How do NCERT Solutions ensure the correct application of Bayes’ Theorem in board-style problems?
These solutions guide you to identify prior and conditional probabilities explicitly, then substitute correctly into Bayes’ Theorem as required by CBSE board exam standards. All calculations follow syllabus-approved logic, helping students avoid common pitfalls and ensuring full marks in proof-based answers.
5. What is the main difference between independent events and mutually exclusive events, and how is this shown in the solutions?
- Independent events: The outcome of one event does not impact the probability of the other. Shown by using the multiplication law P(A ∩ B) = P(A) × P(B).
- Mutually exclusive events: Both cannot occur at the same time. Addressed by the addition law P(A ∪ B) = P(A) + P(B).
NCERT stepwise solutions clarify these with clear event definitions so you apply the correct approach in each case.
6. How can I check if a question from Exercise 13.3 is asking for conditional probability?
Look for phrases like ‘given that’ or wording indicating an event has already occurred. If the problem requires you to find the probability of one event assuming another has happened, use P(A | B). Reading the question carefully for such keywords is essential to avoid applying the wrong formula.
7. Why are stepwise NCERT solutions preferred for Class 12 board exams in probability?
Stepwise solutions help you structure your answer logically, making it easy for examiners to award marks for each stage as per CBSE guidelines. You show clear event definitions, formulas used, substitution, and final boxed answers—this increases accuracy and partial marking opportunities.
8. What key probability formulas should I revise repeatedly before the board exam?
- P(A ∩ B) = P(A) × P(B) (for independent events)
- P(A|B) = P(A ∩ B)/P(B) (conditional probability)
- P(A ∪ B) = P(A) + P(B) – P(A ∩ B) (addition law)
- Bayes’ theorem for reversing conditional probability
Creating a summary sheet with boxed formulas and practicing their usage in multiple questions from Exercise 13.3 reinforces exam readiness.
9. How do these solutions help in differentiating when to use Bayes’ Theorem versus direct conditional probability?
If you need to find the probability of a cause given an observed effect (i.e., reverse probability), Bayes’ Theorem is used. If you are calculating the probability of an event with another already occurring, use direct conditional probability. The solutions walk you through both situations in the syllabus context.
10. What strategies improve accuracy when answering probability word problems in the board exam?
- Define all events and what is ‘given’ before you start calculations
- Draw probability trees or diagrams for clarity if needed
- Check if the question involves dependency or independence
- Double-check denominators in conditional calculations
- Practice with a variety of solved examples from the NCERT Exercise 13.3
11. In what ways are conditional probability and independence of events tested in Exercise 13.3?
Exercise 13.3 includes questions where you assess if two events are independent (their joint probability equals the product of their probabilities) and apply conditional probability when the occurrence of one event affects the probability of another. Some problems require you to use both concepts together to test conceptual understanding.
12. How do NCERT Solutions address the hardest board-style questions on probability?
The hardest questions usually combine multiple concepts, such as Bayes’ Theorem, conditional probability, and event independence. NCERT Solutions demonstrate how to break down such problems into smaller definable events, guide through all steps, and highlight where most students make mistakes, providing strategies for systematic, accurate answers.
13. What should I do if I get confused between mutually exclusive and independent events in a problem?
Remember that mutually exclusive events never occur together (P(A ∩ B) = 0), while independent events can occur together but do not influence each other’s probabilities. Re-read definitions in the NCERT textbook and review example problems that clarify these distinctions.
14. How are real-life scenarios like medical tests or coin tosses represented in probability solutions?
Real-life scenarios are translated into defined events (such as test outcomes as A/B, or heads/tails). The NCERT Solutions teach students to model these with formal probability language, apply the appropriate formulas, and interpret results as per the Class 12 Maths syllabus for probability.

















