CBSE Class 8 Annual Assessment

Annual assessment for Class 8 students under CBSE, focusing on advanced concepts in core subjects to prepare for higher secondary education.

Fractions in Disguise — Class 8 Mathematics

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Mathematics · 14 chapters
Summary, key terms, important questions and a practice quiz with AI diagnosis for each.

Chapter 1: Fractions in Disguise

Summary

This chapter reveals percentages as fractions in disguise. The word per cent comes from the Latin per centum, meaning out of a hundred, so a percentage is simply a fraction with denominator \(100\): \(25\% = \dfrac{25}{100}\). Any fraction can be expressed as a percentage by finding an equivalent fraction with denominator \(100\), for example \(\dfrac{3}{4} = \dfrac{75}{100} = 75\%\), or by multiplying the fraction by \(100\). Conversely, a percentage is converted back to a fraction or decimal by dividing by \(100\). The chapter shows how percentages let us compare proportions on a common scale even when the underlying totals differ, which is exactly why they are so widely used in marks, discounts and statistics. Finding a percentage of a quantity means taking that fraction of it, so \(50\%\) of \(s\) is \(\dfrac{1}{2}s\). These tools connect fractions, decimals and percentages into a single flexible language for describing parts of a whole.

Percentages as fractionsExpressing fractions as percentagesConverting between fractions, decimals and percentagesFinding a percentage of a quantityComparing proportions

Key terms

Per cent
A fraction with denominator \(100\); the symbol \(\%\) means out of every hundred.
Percentage
A way of writing a proportion as parts per hundred, e.g. \(33\% = \dfrac{33}{100}\).
Equivalent fraction
A fraction of equal value with a different denominator, used to reach denominator \(100\).
Fraction-to-percent
Multiplying a fraction by \(100\) (or scaling its denominator to \(100\)) to express it as a percentage.
Percent of a quantity
Taking that fraction of the quantity; \(p\%\) of \(s\) equals \(\dfrac{p}{100} \times s\).
Common scale
The benefit of percentages: proportions from different totals can be compared on a base of \(100\).

Important questions

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Practice quiz

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Class 8 Maths — Fractions in Disguise (Practice Quiz)

10 Qs · ~10 min