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Learn: Ratio and Proportion
iGCSE Mathematics
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Welcome!Today we'll learn about ratio and proportion. This is an important topic that helps us compare quantities and solve real-world problems. Let's explore step by step!
What is a Ratio?A ratio is a way to compare two or more quantities. It shows how much of one thing there is compared to another. For example, if there are 2 apples and 3 oranges, the ratio of apples to oranges is 2:3.
Quick check: What does a ratio represent?
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What is Proportion?Proportion shows that two ratios are equal. For example, if 2:3 is proportional to 4:6, it means the relationship between the numbers in the first ratio is the same as in the second.
A proportion compares two {{blank0}} and shows whether they are {{blank1}}.
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Simplifying RatiosTo simplify a ratio, divide both parts by their greatest common divisor (GCD). For example, to simplify 12:8, divide both numbers by their GCD, which is 4. This gives 3:2.
Quick check: What is the simplified form of the ratio 15:25?
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Using Ratios to Divide QuantitiesWe can use ratios to divide quantities into parts. For example, if £80 is divided in the ratio 3:2, first add the parts (3 + 2 = 5). Then divide £80 by 5 to find the value of one part (£80 ÷ 5 = £16). Multiply each part by £16: 3 × £16 = £48 and 2 × £16 = £32. So the amounts are £48 and £32.
Match the items on the left with their correct pairs on the right
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Proportional ReasoningProportional reasoning lets you solve problems using relationships between quantities. For example, if 3 pens cost £6, how much do 5 pens cost? First, find the cost of 1 pen (£6 ÷ 3 = £2), then multiply by 5 (£2 × 5 = £10).
If 8 oranges cost £4, the cost of 2 oranges is {{blank0}}.
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Review Time!Great work! You've learned about ratios, proportions, simplifying ratios, and proportional reasoning. Now let's test your understanding with a few questions.
Which of the following are examples of ratios? (Select all that apply)
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Match the items on the left with their correct pairs on the right
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Match the items on the left with their correct pairs on the right
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If the ratio of red to blue pencils is 4:6, the simplified ratio is {{blank0}}:{{blank1}}.
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