Comparison of Ratios in
Decimal Form
Jen Kershaw
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Printed: April 24, 2015
AUTHOR
Jen Kershaw
www.ck12.org
C HAPTER
Chapter 1. Comparison of Ratios in Decimal Form
1
Comparison of Ratios in
Decimal Form
Here you’ll learn to write and compare ratios in decimal form.
Remember Casey and the milk comparison in the Ratios in Simplest Form Concept? Well, look at what she is up to
now.
Casey decided to hold a survey about the milk choices of customers at the supermarket. She discovers that many
people purchase regular milk and half as many purchase organic milk. Casey surveyed 50 people.
Here is what she found.
35 out of 50 purchased regular milk.
15 out of 50 purchased organic milk.
If Casey wanted to think about these ratios as decimals, could she do it? What would the decimals be for each
choice?
This Concept will teach you how to do these conversions.
Guidance
Previously we worked on writing ratios in fraction form and simplifying them. What about decimal form? Fractions
and decimals are related, in fact a fraction can be written as a decimal and a decimal can be written as a fraction.
Is it possible to write a ratio as a decimal too?
Yes! Because a ratio can be written as a fraction, it can also be written as a decimal. To do this, you will need
to remember how to convert fractions to decimals.
Now we can apply this information to our work with ratios.
Convert 2:4 into a decimal.
First, write it as a ratio in fraction form.
2:4=
2
4
1
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Next, simplify the fraction if possible.
2 1
=
4 2
Finally, convert the fraction to a decimal.
.5
2)1.0
Our answer is .5.
Practice by converting each ratio to decimal form.
Example A
4 to 5
Solution: .80
Example B
5
20
Solution: .25
Example C
6 to 10
Solution: .60
Now let’s go and help Casey convert her ratios into decimal form. Here is the original problem once again.
Remember Casey and the milk comparison? Well, look at what she is up to now.
Casey decided to hold a survey about the milk choices of customers at the supermarket. She discovers that many
people purchase regular milk and half as many purchase organic milk. Casey surveyed 50 people.
Here is what she found.
35 out of 50 purchased regular milk.
15 out of 50 purchased organic milk.
2
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Chapter 1. Comparison of Ratios in Decimal Form
If Casey wanted to think about these ratios as decimals, could she do it? What would the decimals be for each
choice?
First, we can write a ratio in fraction form. We can use convert the ratios.
35
50
=
70
100
15
50
=
30
100
The first decimal is .70.
The second decimal is .30.
Guided Practice
Here is one for you to try on your own.
Write 2 out of 25 as a decimal.
Answer
To write this ratio as a decimal, we can use a denominator of 100 and create equal fractions.
2
25
=
?
100
Next, we figure out the unknown quantity.
25 times 4 = 100
2 times 4 = 8
8
100
Our answer is .08.
Video Review
MEDIA
Click image to the left or use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/1358
James Sousa, Introduction to Ratios
MEDIA
Click image to the left or use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/5408
James Sousa, Example of Writing a Ratio as a Simplified Fraction
3
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MEDIA
Click image to the left or use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/5409
James Sousa, Another Example of Writing a Ratio as a Simplified Fraction
Explore More
Directions: Convert the following ratios into decimals.
1. 3 to 4
2. 2 to 4
3.
1
5
4. 25 to 100
5. 16 to 32
6. 4 out of 5
7. 6 out of 20
8.
1
4
9. 5 to 6
10. 1:2
11. 4:10
12. 10:50
13. 75 to 100
14. 1 to 3
15. 6 to 8
4