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Formula Sheet

Proportional Reasoning-1 — Formula Sheet

CBSE · Class 8 · Mathematics

18 formulas from Proportional Reasoning-1 (CBSE Class 8 Mathematics) on one page, grouped by topic. Part of the CBSE Class 8 Mathematics syllabus.

55 questions60 flashcards18 formulas & key relations5 concepts

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18 Entries · 7 Sections

Formulas and Key Relations

Similarity and Proportionality

60 : 40

30 : 20

90 : 60

a : b :: c : d

Finding Simplest Form

Divide both terms by HCF

60 ÷ 20 : 40 ÷ 20 = 3 : 2

90 ÷ 30 : 60 ÷ 30 = 3 : 2

Proportional Reasoning and Cross Multiplication

c = fa

d = fb

f = c/a and f = d/b

c/a = d/b

bc = ad or ad = bc

Rule of Three and Āryabhaṭa

pramāṇa × ichchhāphala = phala × ichchhā

Multiply the phala by the ichchhā and divide the resulting product by the pramāṇa.

Cross Multiplication and Unknown Terms

From proportional ratios, f = c/a and f = d/b.

Image A has width:height = 60:40.

Image C has width:height = 30:20.

The unknown fourth term can be found by d = bc/a.

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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 many formulas are in Proportional Reasoning-1?
This sheet lists 18 formulas from Proportional Reasoning-1, grouped by topic. Learn what each symbol stands for so you can apply the formula, not just recall it.
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.

More resources for Proportional Reasoning-1

All CBSE Class 8 Mathematics Formula Sheet

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