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What are proportions used for?
Why do we write proportions?
What does proportion mean?
What is the difference between a ratio and a proportion?
Feb 28, 2024 · In this book, we will use the word proportion to mean any equation that looks like this: a b = c d (1.4.3) where a, b, c, and d will usually be numbers or variables. The reasons we care about proportions is that they give us a way to find an unknown part of one of the ratios involved.
- Overview
- What are ratios and proportions?
- What skills are tested?
- How do we write ratios?
- How do we use proportions?
- Your turn!
- Things to remember
What are ratios and proportions?
A ratio is a comparison of two quantities. The ratio of a to b can also be expressed as a:b or ab .
[Examples]
A proportion is an equality of two ratios. We write proportions to help us establish equivalent ratios and solve for unknown quantities.
A ratio is a comparison of two quantities. The ratio of a to b can also be expressed as a:b or ab .
[Examples]
A proportion is an equality of two ratios. We write proportions to help us establish equivalent ratios and solve for unknown quantities.
[Example]
•Identifying and writing equivalent ratios
•Solving word problems involving ratios
Two common types of ratios we'll see are part to part and part to whole. For example, when we make lemonade:
•The ratio of lemon juice to sugar is a part-to-part ratio. It compares the amount of two ingredients.
•The ratio of lemon juice to lemonade is a part-to-whole ratio. It compares the amount of one ingredient to the sum of all ingredients.
part:whole=part:sum of all parts
To write a ratio:
1.Determine whether the ratio is part to part or part to whole.
If we know a ratio and want to apply it to a different quantity (for example, doubling a cookie recipe), we can use proportional relationships, or equations of equivalent ratios, to calculate any unknown quantities.
a:b=c:dab=cd
To use a proportional relationship to find an unknown quantity:
1.Write an equation using equivalent ratios.
2.Plug in known values and use a variable to represent the unknown quantity.
3.If the numeric part of one ratio is a multiple of the corresponding part of the other ratio, we can calculate the unknown quantity by multiplying the other part of the given ratio by the same number.
TRY: WRITING A RATIO
A pancake recipe uses 14 cup of all-purpose flour and 14 cup of rice flour. What is the ratio of all-purpose flour to rice flour in the recipe?
Choose 1 answer:
Choose 1 answer:
•(Choice A)
1:4
A ratio is a comparison of two quantities.
A proportion is an equality of two ratios.
To write a ratio:
1.Determine whether the ratio is part to part or part to whole.
2.Calculate the parts and the whole if needed.
3.Plug values into the ratio.
Proportions. Proportion says that two ratios (or fractions) are equal. Example: We see that 1-out-of-3 is equal to 2-out-of-6. The ratios are the same, so they are in proportion. Example: Rope. A rope's length and weight are in proportion. When 20m of rope weighs 1kg , then: 40m of that rope weighs 2kg. 200m of that rope weighs 10kg. etc. So:
Aug 15, 2020 · In this section, we equate ratio and rates in a construct called a proportion.
Intro to proportional relationships. To know if a relationship is proportional, you should look at the ratios between the two variables. If the ratio is always the same, the relationship is proportional. If the ratio changes, the relationship is not proportional.
- 4 min
A proportion is a statement that says that two ratios are equal. They can be used in many everyday situations like comparing sizes, cooking, calculating percentages, and more. Proportions can be written as equivalent fractions or as equal ratios. Example.
