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For the use of ratio as a human capacity, see reason.A ratio is a dimensionless, or unitless, quantity denoting an amount or magnitude of one quantity relative to another. Fractions and Percentages are both specific applications of ratios. Fractions relate the part (the numerator) to the whole (the denominator) while percentages always relate the parts per hundred. Throughout the physical sciences, ratios of physical quantities are treated as real numbers. For example, the ratio of metres to 1 metre is the real number . That is m/1m = . Accordingly, the classical definition of measurement is the estimation of a ratio between a quantity and a unit of the same kind of quantity. The term ratio is also used to denote one proportion of a whole relative to the other proportion. With such usage, the ratio is usually written as two numbers separated by a colon (:) which is read as the word "to". A ratio of 2:3 ("two to three") means that the whole is made up of 2 parts of one thing and 3 parts of another — thus, the whole contains five parts in all. To be specific, if a basket contains 2 apples and 3 oranges, then the ratio of apples to oranges is 2:3. If another 2 apples and 3 oranges are added to the basket, then it will contain 4 apples and 6 oranges, resulting in a ratio of 4:6, which is equivalent to a ratio of 2:3 (thus ratios "reduce" like regular fractions). In both cases, there are 2/3 as many apples as oranges in the basket, or 3/2 as many oranges as apples. Note that in the previous example the proportion of apples in the basket is 2/5 ("two of five" fruits, "two out of five" fruits, "two fifths" of the basket, or 40% of the basket). Thus a proportion compares part to whole instead of part to part. A rate is a special kind of ratio in which the two quantities being compared are of different units. The units of a rate are the units of the first quantity "per" unit of the second — for example, a rate of speed or velocity can be expressed in "miles per hour". In algebra, two quantities having a constant ratio are in a special linear relationship called proportionality.
More examples Ratio analysis More colloquially, a ratio is a value calculated by dividing one number by another. Five divided by two gives a "ratio" of 2.5. (More accurately, this gives a ratio of 2.5:1, but this shortcut disregards the latter half in favor of simpler math.) In the business world it is typical to use ratios to analyze financial statements. For example, the current ratio assesses liquidity, or time required for some asset to be converted to cash. The current ratio looks at current assets relative to current liabilities. One indicator, or ratio, for strength or stability of revenue in government is own source revenues (property taxes, for example) divided by total revenues (property tax and outside grants). In some respects, a high ratio suggests safety and stability. Grants or intergovernmental revenues can be taken away and heavy reliance on these outside sources, which would produce a low ratio, can spell trouble for a state or local government. See also | ||||||||
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