Primary mathematics/Proportions
From Wikiversity
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Educational level: this is a primary education resource. |
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Educational level: this is a secondary education resource. |
Ratios are similar to fractions. X:y = x/(x+y). Remember, The proportion x:y does not equal the fraction x/y.
For example, if the ratio of boys to girls in a classroom is 1:2, that does not mean half of the class is boys and the other half is girls. It means that 1/3 of the class is boys and 2/3 of the class is girls.
But remember that the fraction only applies to the sum of the two sides (x+y), and can be wrong if there are more than 3 things.
For example, if there is a fruit basket that has 16 fruits, and the ratio of apples to oranges is 3:1, that doesn't always mean that there are 12 apples ((3/4)*16) and 4 oranges ((1/4)*16). There could be 9 bananas in the fruit basket, which means that there are only 3 apples and one orange.
