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Proportional Reasoning-1 — Revision Notes

CBSE · Class 8 · Mathematics

Proportional Reasoning-1 revision notes for CBSE Class 8 Mathematics: 4 topics in quick points. Part of the CBSE Class 8 Mathematics syllabus.

55 questions60 flashcards18 formulas & key relations5 concepts

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Key Topics to Revise

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.

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Full Notes

Key Concepts

A ratio compares two quantitiesTwo ratios are proportional when theirA ratio is reduced to simplestForĀryabhaṭa called proportionality problems Rule

Frequently Asked Questions

What are the important topics in Proportional Reasoning-1 for CBSE Class 8 Mathematics?
Key topics in Proportional Reasoning-1 include Ratios and Similar Images, Checking Whether Ratios Are Proportional, Cross Multiplication and Unknown Terms, Rule of Three and Āryabhaṭa. Study these first, then practise questions on each for Class 8 exams.
How should I revise Proportional Reasoning-1 for Class 8 exams?
Learn the core ideas first, then work through the 55 practice questions on Proportional Reasoning-1. Revise 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 CBSE Class 8 Mathematics Revision Notes

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