GCSE Maths Ratio and Proportion: lesson and practice questions

By the end of this chapter you will be able to

• Write one quantity as a fraction of another, including when the fraction is bigger than 1 and when the units are different
• Write ratios, simplify them (with different units, decimals and fractions) and write them in the form 1 : n
• Share a quantity in a given ratio, and solve problems where one part or the difference is known
• Combine ratios such as a : b and b : c, and move between ratios and fractions
• Use ratio in recipes, mixing, concentrations and conversions
• Use the unitary method and unit prices to solve proportion problems and find the best buy
• Use proportion as equality of ratios and connect it to the linear function y = kx

You should already know

• Simplifying fractions and finding fractions of an amount (Chapter 3)
• Multiplying and dividing whole numbers and decimals (Chapters 1 and 4)
• Highest common factor (Chapter 2)
• Converting between units of length, mass and time

Where this leads

• Percentages and percentage change (Chapter 5)
• Direct and inverse proportion, speed, density and pressure (Chapter 16)
• Straight-line graphs and gradient (Chapter 12)
• Scale factors and similar shapes (Chapter 21)
• Probability as a fraction (Chapter 23)