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Parts and Wholes - Equivalent Fractions

Grade 5CBSE

Review the key concepts, formulae, and examples before starting your quiz.

๐Ÿ”‘Concepts

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A fraction represents a part of a whole or a collection. For example, if a circular pizza is cut into 4 equal slices, each slice is represented as 14\frac{1}{4} of the whole pizza.

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In any fraction ab\frac{a}{b}, the top number 'aa' is called the Numerator (the number of parts we have) and the bottom number 'bb' is the Denominator (the total number of equal parts the whole is divided into). Visually, if a rectangle is divided into 5 equal strips and 3 are shaded, the fraction is 35\frac{3}{5}.

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Equivalent Fractions are different fractions that name the same amount or part of a whole. Imagine two identical chocolate bars: one divided into 2 equal halves (where you eat 1) and another divided into 4 equal quarters (where you eat 2). In both cases, you have eaten the same amount because 12=24\frac{1}{2} = \frac{2}{4}.

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To find an equivalent fraction, multiply both the numerator and the denominator by the same non-zero number. For example, 23\frac{2}{3} becomes 46\frac{4}{6} if you multiply both parts by 2. This is like taking a shaded area and cutting all existing parts into smaller equal pieces.

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Equivalent fractions can also be found by dividing both the numerator and the denominator by their common factor. For instance, the fraction 1020\frac{10}{20} can be simplified to 12\frac{1}{2} by dividing both the top and bottom by 10.

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You can test if two fractions ab\frac{a}{b} and cd\frac{c}{d} are equivalent using cross-multiplication. If the product of aร—da \times d is equal to the product of bร—cb \times c, the fractions are equivalent.

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A fraction is in its simplest form when the only common factor between the numerator and denominator is 1. For example, 34\frac{3}{4} is in simplest form, whereas 68\frac{6}{8} is not because both 6 and 8 can be divided by 2.

๐Ÿ“Formulae

ab=aร—nbร—n\frac{a}{b} = \frac{a \times n}{b \times n} (where nโ‰ 0n \neq 0)

ab=aรทnbรทn\frac{a}{b} = \frac{a \div n}{b \div n} (where nn is a common factor)

ab=cdโ€…โ€ŠโŸบโ€…โ€Šaร—d=bร—c\frac{a}{b} = \frac{c}{d} \iff a \times d = b \times c

๐Ÿ’กExamples

Problem 1:

Find an equivalent fraction of 45\frac{4}{5} that has a denominator of 20.

Solution:

Step 1: Determine what number the current denominator 5 must be multiplied by to get 20. 20รท5=420 \div 5 = 4 Step 2: Multiply both the numerator and the denominator of 45\frac{4}{5} by this number (4). 4ร—45ร—4=1620\frac{4 \times 4}{5 \times 4} = \frac{16}{20} Therefore, 1620\frac{16}{20} is the equivalent fraction.

Explanation:

To keep a fraction equivalent, any operation performed on the denominator must also be performed on the numerator. Since the denominator was scaled up by 4, we scale the numerator by 4 as well.

Problem 2:

Check whether 38\frac{3}{8} and 924\frac{9}{24} are equivalent fractions.

Solution:

Step 1: Use the cross-multiplication method. Multiply the numerator of the first fraction by the denominator of the second fraction: 3ร—24=723 \times 24 = 72 Step 2: Multiply the denominator of the first fraction by the numerator of the second fraction: 8ร—9=728 \times 9 = 72 Step 3: Compare the two results. Since 72=7272 = 72, the fractions are equivalent.

Explanation:

If the cross-products of two fractions are equal, it confirms that the ratio between the parts and the whole is identical for both fractions.