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Proportional Reasoning-1

CBSE · Class 8 · Mathematics

Complete topic list for Proportional Reasoning-1 in CBSE Class 8 Mathematics. Key concepts, sub-topics, and what to focus on for board exams.

55 questions60 flashcards5 concepts

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4 Topics · CBSE Class 8 Mathematics

Topics in Proportional Reasoning-1

1

1. Ratios and Similar Images

  • The ratio of width to height of image A is 60:40.
  • The numbers 60 and 40 are called the terms of the ratio.
  • In a ratio a:b, for every a units of the first quantity there are b units of the second quantity.
2

2. Checking Whether Ratios Are Proportional

  • A quick test for proportionality is to reduce both ratios to simplest form.
  • The ratios 3:4 and 72:96 are proportional.
  • 3:4 is already in simplest form.
3

3. Cross Multiplication and Unknown Terms

  • For a:b::c:d, the terms change by the same factor.
  • If c = fa and d = fb, then both ratios stay proportional.
  • From proportional ratios, f = c/a and f = d/b.
4

4. Rule of Three and Āryabhaṭa

  • Āryabhaṭa and others called proportionality problems Rule of Three problems.
  • The three given numbers in Rule of Three were pramāṇa, phala, and ichchhā.
  • The unknown to be found is ichchhāphala.

Key Concepts

Central concept: Proportional reasoning

Similarity in changeRatioSimplest formProportionCross multiplicationRule of ThreeScaling with the same factorWorked example: lemonade

Frequently Asked Questions

What are the important topics in Proportional Reasoning-1 for CBSE Class 8 Mathematics?
Proportional Reasoning-1 covers several key topics that are frequently asked in CBSE Class 8 board exams. Focus on the core concepts listed on this page and practise related questions to build confidence.
How to score full marks in Proportional Reasoning-1 — CBSE Class 8 Mathematics?
Understand the core concepts first, then work through the 55 practice questions available for this chapter. Revise formulas and definitions regularly, and use flashcards for quick recall before the exam.

Sources & Official References

Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.

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All 14 chapters — CBSE Class 8 Mathematics Syllabus

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