Meaning & use
ratio
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Meanings
nouncountable
A way of comparing two amounts that shows how many times one contains the other, written like 3:1.
Grammar: Followed by of and to: a ratio of two to one.
Patterns
- the ratio of A to B
- in a ratio of something
The ratio of boys to girls in the class is three to two.
Mix the paint and water in a ratio of one to four.
The recipe uses a ratio of two parts flour to one part butter.
nouncountable
The relationship between two numbers or amounts that shows how large one is compared with the other, used more loosely in everyday talk.
Grammar: Often used with another noun: student-teacher ratio.
Patterns
- a high ratio of something
- a low ratio of something
The school has a very low student-teacher ratio.
Investors check the debt-to-income ratio before lending.
The ratio of cost to benefit was too high.
Word forms
| plural | ratios |
|---|
Common combinations
- in a ratio of
- The tiles are mixed in a ratio of two to one.
- gear ratio
- A low gear ratio helps the bike climb hills.
- student-teacher ratio
- The student-teacher ratio is twenty to one.
- aspect ratio
- The screen has a wide aspect ratio.
- ratio of A to B
- The ratio of salt to water is crucial.
- golden ratio
- Artists have long admired the golden ratio.
Synonyms and how they differ
- proportion
- Proportion compares a part with the whole, while ratio compares two amounts directly.
- rate
- Rate compares different units, like miles per hour, while ratio compares like things.
- fraction
- A fraction shows part of a whole as a number, whereas a ratio compares two quantities.
Word family
- rational adjective
- able to be written as a ratio, or sensible
- ration noun
- a fixed share of supplies
- proportion noun
- a related word about parts and wholes
- ratio noun
- from Latin for calculation
Commonly confused: ratio or ration? ratio or rational?
ratio vs ration
A ration is a fixed portion of something in short supply, while a ratio compares two amounts.
ratio vs rational
Rational means sensible or logical, and in math can mean a number written as a ratio.
Practice
The paint is mixed in a ___ of three parts white to one part blue.
Choose one answer.
A ratio compares two amounts. A ration is a portion of supplies and does not fit, and rate compares different units.
Make it your own
Write a sentence using “ratio”, then check it and compare it with the examples above.