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A unit ratio is a ratio with a denominator of 1 unit. Every ratio can be rewritten as a unit ratio.
A ratio is a comparison of two quantities with similar units of measure. Consider writing unit ratios using the relationship between some units of measure. Notice that the denominator of each unit ratio is 1 unit.
The ratio 12 in. 1ft, for example, can be reduced by changing the numerator to 1 foot. The ratio then becomes 1 ft1ft. The units are omitted once they are the same. As a result, the ratio is reduced to 1. Also, note that different ratios can be written using the same relationships.
| Fact | 1 foot is equal to 12 inches. | 1 hour is equal to 60 minutes. |
|---|---|---|
| Ratio | 1ft/12in. | 1h/60min |
The denominators of these ratios are different than 1 unit. Divide both the numerator and denominator of each ratio by the number in the denominator. Then, the denominators will be equal to 1 unit.
These resulting unit ratios mean that 1 inch is approximately 0.083 feet and 1 minute is approximately 0.017 hours. Unit ratios are useful when converting measurement units.