Comparison of Unlike Fractions

In comparison of unlike fractions, we change the unlike fractions to like fractions and then compare.

Let us compare two fractions \(\frac{4}{7}\) and \(\frac{4}{9}\) which have same numerator.

Comparison of Unlike Fractions

Since 4 shaded parts of 7 is bigger than the 4 shaded parts of 9 therefore \(\frac{4}{7}\) > \(\frac{4}{9}\).

To compare two fractions with different numerators and different denominators, we multiply by a number to convert them to like fractions.

Let us consider some of the examples on comparing fractions (i.e. unlike fractions).

1. Which one is greater, \(\frac{4}{7}\) or \(\frac{3}{5}\)?

First we convert these fractions into like fractions. To convert unlike fraction into like fraction first of all find the L.C.M. of their denominators.

L.C.M. of 7 and 5 = 35

Now, divide this L.C.M. by the denominator of both the fractions.

35 ÷ 7 = 5

35 ÷ 5 = 7

Multiply both the numerator and denominator with the number you get after dividing.

i.e., \(\frac{4 × 5}{7 × 5}\) = \(\frac{20}{35}\)

\(\frac{3 × 7}{5 × 7}\) = \(\frac{21}{35}\)

because \(\frac{21}{35}\) > \(\frac{20}{35}\)

So, \(\frac{3}{5}\) > \(\frac{4}{7}\)

We can compare two fractions by cross multiplication also.

Let us solve the above example by cross multiplication. Here, we cross multiply as follows.

By Cross Multiplication

4 × 5 = 20

3 × 7 = 21

Since, 21 > 20

Therefore, \(\frac{3}{5}\) > \(\frac{4}{7}\)

2. Compare 3\(\frac{2}{5}\) and 2\(\frac{3}{4}\).

First we convert these mixed numbers into improper fractions.

2\(\frac{3}{4}\) = \(\frac{4 × 2 + 3}{4}\) = \(\frac{11}{4}\)

3\(\frac{2}{5}\) = \(\frac{5 × 3 + 2}{5}\) = \(\frac{17}{5}\)

Now, we compare \(\frac{11}{4}\) and \(\frac{17}{5}\) by cross multiplication.

Compare By Cross Multiplication

11 × 5 = 55 and 17 × 4 = 68

We see that 68 > 55.

Therefore, \(\frac{17}{5}\) > \(\frac{11}{4}\)  or, 3\(\frac{2}{5}\) > 2\(\frac{3}{4}\)

3. Let us compare \(\frac{5}{7}\) and \(\frac{3}{5}\).

\(\frac{5}{7}\) = \(\frac{5 × 5}{7 × 5}\) = \(\frac{25}{35}\)

Multiply the numerator and denominator by 5.

\(\frac{3}{5}\) = \(\frac{3 × 7}{5 × 7}\) = \(\frac{21}{35}\)

Multiply the numerator and denominator by 7.

Hence, \(\frac{25}{35}\) > \(\frac{21}{35}\)

Therefore, \(\frac{5}{7}\) > \(\frac{3}{5}\)

We will learn an alternative method i.e. cross multiply to compare the given fractions.

4. Let us compare \(\frac{2}{3}\) and \(\frac{4}{5}\).

Compare the Fractions

2 × 5 = 10 and 3 × 4 = 12

Since, 12 > 10, hence \(\frac{4}{5}\) > \(\frac{2}{3}\)

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Related Concept

Fraction of a Whole Numbers

Representation of a Fraction

Equivalent Fractions

Properties of Equivalent Fractions

Like and Unlike Fractions

Comparison of Like Fractions

Comparison of Fractions having the same Numerator

Types of Fractions

Changing Fractions

Conversion of Fractions into Fractions having Same Denominator

Conversion of a Fraction into its Smallest and Simplest Form

Addition of Fractions having the Same Denominator

Subtraction of Fractions having the Same Denominator

Addition and Subtraction of Fractions on the Fraction Number Line

4th Grade Math Activities

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