ISC Class 12 Maths Probability Unit 4 | Specimen & Previous Year Papers | Board Prep 2026

Описание: ISC Class 12 Maths Probability Unit 4
Specimen & Previous Year Papers
Board Prep 2026

Dear Students,
In this video, I presents a complete exam preparation guide for ISC Class 12 Maths – Unit 4 (Probability), a scoring unit carrying 13 marks in the ISC Board Examination.

To ensure thorough preparation for the ISC Board Examination 2026, a single combined PDF of paper has been uploaded containing Specimen Paper and multiple previous year board examination questions of unit 4 probabilty, allowing students to practise extensively from one unit.

📌 The combined PDF of includes:
✔ Specimen Paper Unit 4 Probibility
✔ Specimen Paper 2025 Unit 4 Probibility
✔ Board Examination 2025 Unit 4 Probibility
✔ Board Examination 2024 Unit 4 Probibility
✔ Board Examination 2023 Unit 4 Probibility
✔ Board Examination 2020 Unit 4 Probibility
✔ Board Examination 2019 Unit 4 Probibility
✔ Board Examination 2018 Unit 4 Probibility

📄 Students are strongly advised to download the PDF, take a printout, and practise all questions sincerely for Pre-Board and Final Board Examination preparation 2026.

📘 Unit 4 – Probability Topics Covered:
• Conditional Probability
• Independent and Dependent Events
• Bayes’ Theorem
• Probability Distributions (as per ISC syllabus)

🔹 What this video offers:
✔ Step-by-step solutions of Probability questions
✔ Clear explanation of concepts with board-level problems
✔ Focus on accuracy, logic, and proper mathematical presentation
✔ Strategic guidance on answer writing for full marks
✔ Identification of common mistakes made by students
✔ Ideal revision resource before exams

📌 Why this preparation method is effective:
Practising multiple years’ board questions unit-wise helps students identify question patterns, improve confidence, and score consistently in Probability, one of the most logical and scoring units in ISC Maths.

🎯 This video is ideal for ISC Class 12 students preparing for Board Exams 2026, Pre-Boards, and Final Probability Revision.

👉 Download the PDF, practise regularly, and secure maximum marks in Unit 4 – Probability.
https://drive.google.com/file/d/1WNCz...

Thanks
Dr. Ajay Kumar Gupta
















































































Question no 1 [SP 2025] [1×3] (v) Five numbers x 12x_3 ,x_4 ,x_5 are randomly selected from the numbers 1, 2 , 3 ,………….18 and
are arranged in the increasing order such that What is the probability that x_2=7 and x_4=11 ?
26/51 b) 3/104
1/68 d) 1/34


(xv) There are three machines and 2 of them are faulty. They are tested one by one in a random order till both the faulty machines are identified. What is the probability that only two tests are needed to identify the faulty machines?


(ii) A school offers students the choice of three modes for attending classes:
Mode A: Offline (in-person) – 40% of students
Mode B: Online (live virtual classes) – 35% of students
Mode C: Recorded lectures – 25% of students
After a feedback survey:
20% of students from Mode A reported the class as “Excellent”
30% from Mode B rated it as “Excellent”
50% from Mode C rated it as “Excellent”
A student is selected at random from the entire group, and it is found that they rated the class as “Excellent.”
(a) Represent the data in terms of probability. Define the events clearly.
(b) Using Bayes’ Theorem, find the probability that the student attended the Recorded lectures (Mode C), given that they rated the class as “Excellent.”
(c) Interpret your result. Which mode has the highest likelihood of being chosen if a student says “Excellent”?

Question 14 [6 mark]
In a school, three subject teachers English, Math, and Science sometimes give surprise tests on the same day. Based on past records:
The English teacher gives a test 90% of the time
The Math teacher gives a test 80% of the time
The Science teacher gives a test 70% of the time
Each teacher decides independently. If the average number of surprise tests is less than 2.3 then the teachers should coordinate better to increase the performance of the students. Otherwise, no action is needed.
Let X be the number of surprise tests a student gets on a given day. So, X∈{0,1,2,3}
Find the probability for each possible number of surprise tests.
Use the probabilities to build a distribution table.
Calculate the average number of surprise tests per day.
Based on your calculations, decide: Should the teachers coordinate better? Or is the current plan acceptable?







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