Learn: Ratio and Proportion

Welcome!Today we'll explore Ratio and Proportion, a key topic in iGCSE Mathematics. These concepts help us compare quantities and solve problems involving sharing or scaling. Let’s dive in!

What is Ratio?A ratio shows the relationship between two or more quantities, comparing their sizes. For example, the ratio 2:3 means that for every 2 parts of the first quantity, there are 3 parts of the second quantity.

What is Proportion?Proportion is an equation that states two ratios are equal. For example, if 2:3 is proportional to 4:6, this means the quantities are in the same ratio.

Dividing in a RatioTo divide a quantity in a given ratio, add the parts of the ratio and split the total accordingly. For example, dividing £60 in the ratio 2:3 means splitting it into 5 parts (2+3). Each part is £12 (£60 ÷ 5). So, one person gets £24 (2 parts), and the other gets £36 (3 parts).

Working with ProportionsProportions help solve problems where quantities are scaled up or down. For example, if a recipe for 2 people uses 300g of flour, how much flour is needed for 6 people? The proportion is 2:6 = 300:x. Use cross-multiplication to solve: 2x = 1800, so x = 900g.

Percentage ChangePercentage change compares the change in a value to its original value, expressed as a percentage. The formula is: (Change ÷ Original value) × 100. For example, if a price increases from £50 to £75, the change is £25. Percentage change = (25 ÷ 50) × 100 = 50%.

Review Time!Great work! You've learned about ratio, proportion, dividing in a ratio, and percentage change. Now let's test your understanding with a few questions.

Well Done!You’ve completed the lesson on Ratio and Proportion. Keep practising your skills, and you'll master this topic in no time!