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Fractions - Equivalent Fractions

Grade 5ICSE

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

πŸ”‘Concepts

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Equivalent fractions are fractions that represent the same value or part of a whole, even though they have different numerators and denominators. For example, if you divide a rectangular bar into 2 equal parts and shade 1, or divide it into 4 equal parts and shade 2, the shaded area remains the same: 12=24\frac{1}{2} = \frac{2}{4}.

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To create an equivalent fraction, you can multiply both the numerator and the denominator by the same non-zero number. Visually, this is like taking an existing diagram and drawing more lines to create smaller sub-sections without changing the total colored portion.

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Equivalent fractions can also be found by dividing both the numerator and the denominator by a common factor. This process is known as 'simplification' or 'reducing the fraction'. For instance, if you have 48\frac{4}{8} of a circle shaded, you can group the 4 parts together to see it is equivalent to 12\frac{1}{2}.

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A fraction is in its simplest form (lowest terms) when the numerator and the denominator have no common factors other than 1. On a diagram, the simplest form uses the largest possible equal pieces to represent the portion.

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On a number line, all equivalent fractions are represented by the same point. If you mark 13\frac{1}{3}, 26\frac{2}{6}, and 39\frac{3}{9} on a number line between 0 and 1, all three marks will land on the exact same spot.

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The Cross-Multiplication Method is a quick way to check for equivalence. If you have two fractions ab\frac{a}{b} and cd\frac{c}{d}, they are equivalent if the product of the first numerator and second denominator (aΓ—da \times d) equals the product of the first denominator and second numerator (bΓ—cb \times c).

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When generating a series of equivalent fractions, you are essentially multiplying the original fraction by nn\frac{n}{n} (which is equal to 1). Since multiplying any number by 1 does not change its value, the fractions remain equivalent: 23Γ—22=46\frac{2}{3} \times \frac{2}{2} = \frac{4}{6}.

πŸ“Formulae

ab=a×nb×n\frac{a}{b} = \frac{a \times n}{b \times n} (where n≠0n \neq 0)

ab=aΓ·nbΓ·n\frac{a}{b} = \frac{a \div n}{b \div n} (where nn is a common factor of aa and bb)

IfΒ ab=cd,Β thenΒ aΓ—d=bΓ—c\text{If } \frac{a}{b} = \frac{c}{d}, \text{ then } a \times d = b \times c

πŸ’‘Examples

Problem 1:

Find an equivalent fraction of 37\frac{3}{7} with denominator 35.

Solution:

Step 1: Determine what number the original denominator must be multiplied by to get the new denominator: 35Γ·7=535 \div 7 = 5. \ Step 2: Multiply the numerator by the same number: 3Γ—5=153 \times 5 = 15. \ Step 3: Write the new fraction: 3Γ—57Γ—5=1535\frac{3 \times 5}{7 \times 5} = \frac{15}{35}.

Explanation:

To maintain equivalence, we must multiply the numerator and denominator by the same number. Since the denominator increased by a factor of 5, the numerator must also increase by a factor of 5.

Problem 2:

Are the fractions 46\frac{4}{6} and 1015\frac{10}{15} equivalent? Use cross-multiplication to check.

Solution:

Step 1: Multiply the numerator of the first fraction by the denominator of the second: 4Γ—15=604 \times 15 = 60. \ Step 2: Multiply the denominator of the first fraction by the numerator of the second: 6Γ—10=606 \times 10 = 60. \ Step 3: Compare the products. Since 60=6060 = 60, the fractions are equivalent.

Explanation:

If the cross-products are equal, the two fractions represent the same ratio and are therefore equivalent.