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Introduction to Ratio

Understand and use simple ratios

Introduction to Ratio

A ratio compares two quantities. If there are 3 boys and 5 girls, the ratio of boys to girls is 3:5 (said as '3 to 5'). The order matters!
Example

Writing Ratios

A fruit bowl has 4 apples and 6 oranges. Ratio of apples to oranges = 4:6 Simplified (÷2): 2:3 A recipe uses 2 cups flour and 1 cup sugar. Ratio flour to sugar = 2:1
Example

Using Ratios

Mix paint in ratio 1:3 (white to blue). If you use 2 cups white, you need: 2 × 3 = 6 cups blue. Share R60 in ratio 1:2 between Thabo and Lerato. Parts = 1 + 2 = 3 Thabo gets 1/3 of R60 = R20 Lerato gets 2/3 of R60 = R40
Note

Remember

A ratio compares amounts — the order matters! 3:5 is not the same as 5:3. Simplify ratios by dividing both numbers by their common factor.

Key Vocabulary

RatioA comparison of two quantities using a colon (:)
SimplifyMake a ratio simpler by dividing both parts by the same number
ProportionTwo equal ratios
CompareLook at two or more things to find how they are alike or different

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