ALLCBTs

JEE Mathematics Past Question.

Published on Aug 7, 2025 • Education

Introduction

Welcome to today’s JEE Mathematics tutorial! In this session, we’re diving into a classic probability problem from past questions — a must-know topic for anyone preparing for JEE Main or Advanced.

Let’s get started with the questions and answers.

Question 1

Question:
Two balls are selected at random, one after the other, without replacement, from a bag containing 4 white balls and 6 black balls.
If the probability that the first selected ball is black, given that the second selected ball is also black, is m/m, gcd⁡ (m,n) =1, what is the value of m+n

Step-by-Step Breakdown

Step 1: Total Number of Balls

We are given:

• 4 white balls
• 6 black balls
  Total = 4+6= 10 balls

Final Answer: 14

Watch more educational videos and past questions: https://youtube.com/@allcbts

Why This Matters in JEE Exams.

• Questions like this test your grasp of conditional probability — a high-yield concept in both JEE Main and Advanced.
• Knowing how to deal with “without replacement” is essential for mastering combinatorics and probability.

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