Lesson 9Comparing Fractions

Being able to compare the values of fractions is especially important in the U.S. system of measurement. The metric system virtually eliminates a real need for fractions and comparing values of fractions. Nevertheless, the concepts and thought processes involved in comparing fractional values can prove useful in other areas of modern mathematics.

Consider this example:

One piece of lumber is 5/8" thick and another is 3/4" thick. Which is thicker?

Thinking in terms of a ruler, you can see that 3/4" is larger than 5/8" (even though the fraction 5/8 uses larger numbers)

Here is another situation that calls for comparing fractional values:

At 200° F, the area of a small metal plate is 23/32 in2. At 600° F, the area is found to be 55/64 in2. Does the metal expand or contract as its temperature rises? In other words, is 55/64 larger or smaller than 23/32?

Think about it as you work through the remainder of this lesson.

Topic 1
Comparing Fractions with Common Denominators

 Procedure When comparing two fractions that have a common denominator: Compare the numerators. The fraction with the larger numerator is the larger fraction.

Example:

Which is larger, 3/16 or 5/16 ?

Denominators are the same, and the numerator of 5/16 is larger than the numerator of 3/16

So 5/16 > 3/16

Indicate the fraction that has the larger value.

Topic 2
Comparing Fractions that Do Not Have Common Denominators

 Procedure When two fractions do not have the same denominator: Adjust the fractions so that they have a common denominator. Compare the numerators. The fraction with the larger numerator is the larger fraction.

Example:

Which is larger, 4/5 or 3/4 ?
1. Rewriting the fractions to have a common denominator:

16/20 or 15/20

1. The numerator of 16/20 is larger than the numerator of 15/20.

So 4/5 > 3/4

Exercise

Indicate the fraction that has the larger value.

Topic 3
Comparing Mixed Fractions

 Procedure When comparing mixed fractions, the one with the larger whole-number part is the larger number — provided the fraction part is a proper fraction. Rewrite any improper fraction as a proper fraction. Compare the whole-number values. The fraction with the larger whole-number part is the larger value..

Example:

Which is larger, 110/5 or 2 3/4 ?

The fraction part 10/5 is not a proper fraction -- it is actually equal to 2. So when 110/5 is rewritten as a proper fraction, it becomes 3.

Now, which is larger,   3 or  2 3/4
Of course 3 is larger than 2 3/4. So:

So 110/5 is larger than 2 3/4

Exercise

Indicate the fraction or mixed number that has the larger value.

 If you are having any trouble understanding the content of this lesson, you will benefit from a more detailed tutorial on the subject.