Class 8 Maths Part 1 Chapter 7 PDF: Proportional Reasoning-1 (Ganita Prakash)

Class 8 Maths Part 1 Chapter 7, Proportional Reasoning-1, starts with resized tiger photographs—why some look undistorted while others look stretched—to introduce ratios, simplest form, proportions, Bhāskarāchārya’s Trairāśika (Rule of Three) and unequal sharing.

What Class 8 Maths Chapter 7 Covers

7.1 Observing Similarity in Change, 7.2 Ratios, and 7.3 Simplest Form show why proportional change preserves aspect ratio and taste, and how to reduce ratios to their simplest form.

7.4 Problem Solving with Proportional Reasoning solves proportion word problems using the unitary method, equivalence of ratios and the ancient Indian Trairāśika (Rule of Three — pramāṇa, phala and ichchhā) with problems from Līlāvatī.

7.5 Sharing, but Not Equally! and 7.6 Unit Conversions divide quantities in a given ratio a : b and apply proportional reasoning to unit conversions, closing with Binairo logic puzzles.

Exercises in Chapter 7

• Figure it Out exercise sets after each major section, with complete answer keys at the end of the chapter.

Read Class 8 Maths Chapter 7 Online

More Chapters

• Previous: Chapter 6: We Distribute, Yet Things Multiply
• Hindi medium: Class 8 Maths Part 1 Chapter 7 PDF in Hindi (Ganita Prakash)
• All Maths chapters and the other Class 8 books: Class 8 NCERT books 2026-27
• All Class 1 to 12 NCERT Textbooks: NCERT Books PDF (Class 1–12)
• Every book chapter by chapter: NCERT chapter wise PDF

FAQ

What is Trairāśika in Class 8 Maths Chapter 7?
The ancient Indian ‘Rule of Three’ (with three known quantities: pramāṇa, phala and ichchhā) used by Āryabhaṭa, Brahmagupta and Bhāskarāchārya to solve proportion problems.

How do you divide a quantity W in the ratio a : b?
The two parts are a/(a + b) × W and b/(a + b) × W.

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