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Write ratios as fractions

A ratio comparing one quantity to another can be written as a fraction: aa to bb or a:ba:b is represented by ab\frac{a}{b}, with the first quantity in the numerator and the second in the denominator. This fraction expresses a multiplicative comparison, not automatically a part of a whole; reversing the terms changes the relationship. The focus is on positive whole-number quantities, without more advanced algebraic generalizations.

Detailed Explanation: Write ratios as fractions

A ratio compares two quantities in a specific order.

  • The first quantity goes in the numerator.
  • The second quantity goes in the denominator.

So,

a to b=a:b=aba\text{ to }b=a:b=\frac{a}{b}

Example

A box has 66 green pencils and (10)(10) yellow pencils. Write the ratio of green pencils to yellow pencils as a fraction.

Step 1: Identify the quantities in order.

The ratio is green to yellow:

  • Green pencils: 66
  • Yellow pencils: (10)(10)

Step 2: Put the first quantity on top and the second quantity on the bottom.

green to yellow=610\text{green to yellow}=\frac{6}{10}

So, the ratio of green pencils to yellow pencils as a fraction is

610\boxed{\frac{6}{10}}

The order matters. The ratio of yellow pencils to green pencils would be 106\frac{10}{6}, which describes a different comparison.

Learn by doing: Write ratios as fractions

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Ratios - Calculate Item Ratio from Values


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