In comparison of unlike fractions, we change the unlike fractions to like fractions and then compare.
Let us consider some of the examples on comparing fractions (i.e. unlike fractions).
1. Which one is greater, 4/7 or 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., 4 × 5/7 × 5 = 20/35
3 × 7/5 × 7 = 21/35
because 21/35 > 20/35
So, 3/5 > 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.
4 × 5 = 20
3 × 7 = 21
Since, 21 > 20
Therefore, 3/5 > 4/7
2. Compare 3 2/5 and 2 ¾.
First we convert these mixed numbers into improper fractions.
2 ¾ = (4 × 2) + ¾ = 11/4
3 2/5 = (5 × 3) + 2/5 = 17/5
Now, we compare 11/4 and 17/5 by cross multiplication.
11 × 5 = 55 and 17 × 4 = 68
We see that 68 > 55.
Therefore, 17/5 > 11/4 or, 3 2/5 > 2 ¾
Related Concept
● Representation of a Fraction
● Properties of Equivalent Fractions
● Comparison of Like Fractions
● Comparison of Fractions having the same Numerator
● 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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