**Ratio and proportion:** In mathematics, a **ratio** indicates how many times one number contains another. For example, if there are eight oranges and six lemons in a bowl of fruit, then the ratio of oranges to lemons is eight to six (that is, 8∶6, which is equivalent to the ratio 4∶3). Similarly, the ratio of lemons to oranges is 6∶8 (or 3∶4) and the ratio of oranges to the total amount of fruit is 8∶14 (or 4∶7).

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- Ratio, Proportion and Unitary Method.
- The comparison of two numbers or quantities by division is known as the ratio. Symbol ‘:’ is used to denote ratio.
- For a ratio, the two quantities must be in the same unit. If they are not, they should be expressed in the same unit before the ratio is taken.
- A ratio may be treated as a fraction.
- Two ratios are equivalent, if the fractions corresponding to them are equivalent.
- Four quantities are said to be in proportion, if the ratio of the first and the second quantities is equal to the ratio of the third and the fourth quantities. The symbol ‘::’ or ‘=’ is used to equate the two ratios.
- The order of terms in a proportion is important. For example 3, 8, 24, 64 are in proportion but 3, 8, 64, 24 are not in proportion.
- The method in which first we find the value of one unit and then the value of the required number of units is known as unitary method.