Introduction to Probability Exercise 7.4 Class 9 Maths Solutions

The Introduction to Probability Exercise 7.4 set brings the chapter together with tree diagrams and multi-step picks. These NCERT Solutions Class 9 Maths Chapter 7 Introduction to Probability Exercise 7.4 solve both questions in clear steps, matched to the new Ganita Manjari book, so you can handle combined events with ease.

• Questions solved: both questions on tree diagrams and combined picks.
• Main skill: multiplying branch probabilities along a path.
• Chapter link: it pulls together sample spaces and probability from earlier sets.

These solutions are written by subject teachers, matched to the current 2026-27 NCERT book, and checked line by line so a Class 9 student can follow each branch.

What Does Class 9 Maths Chapter 7 Introduction to Probability Exercise 7.4 Cover?

This exercise deals with experiments that happen in two steps. A tree diagram shows each step as branching paths. The first level is the first pick, and the second level is the second pick. When the two picks do not affect each other, they are independent, and the probability along a full path is the product of its branch probabilities. You also count all the paths to build the sample space and find the chance of a chosen pair. The set closes the chapter by joining the counting from Exercise 7.3 with the probability formula from Exercise 7.2. A tree diagram keeps this work tidy, since each path leads to exactly one outcome and one fraction.

Video Walkthrough

Source: Magnet Brains on YouTube

Introduction to Probability Exercise 7.4 Question Breakdown

Exercise 7.4 has two questions. The bullets below show what each one asks, so you can plan your practice.

• Q1: two fruit baskets, draw a tree diagram, list the sample space, and find the chance of one apple and one banana.
• Q2: a box of coloured pens, find probabilities for the pens drawn from it.

Sample Solved Question from Exercise 7.4

Here is Question 1, solved step by step, so you can see how a tree diagram works.

Question: Basket A has one apple and two oranges. Basket B has one banana and one mango. You pick one fruit from each basket. Find the probability of picking one apple and one banana.

Step 1. Find the branch chances for Basket A. It has one apple and two oranges, so P(apple)=13.

Step 2. Find the branch chances for Basket B. It has one banana and one mango, so P(banana)=12.

Step 3. The two picks are independent, so multiply along the path: P(apple and banana)=13×12.

Final answer. The probability is P(apple and banana)=16.

How to Use These Introduction to Probability Exercise 7.4 Solutions

Draw the tree diagram yourself before you read ours, then use these Collegedunia solutions to check your branches and your final products. Getting the branch fractions right is the part where most marks are won or lost in this exercise.

• Write the fraction on every branch, not just at the end.
• Multiply the fractions along one path to get that outcome's chance.
• Add all the path fractions and confirm the total is 1.

More Class 9 Maths Introduction to Probability Solutions

Use the table below to open the full chapter or any other exercise of this chapter.