NumberDeep Dive

Method: Direct Proportion

Part of Proportion — GCSE Mathematics

This deep dive covers Method: Direct Proportion within Proportion for GCSE Mathematics. Revise Proportion in Number for GCSE Mathematics with 12 exam-style questions and 22 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 4 of 15 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.

Topic position

Section 4 of 15

Practice

12 questions

Recall

22 flashcards

Method: Direct Proportion

1 Write y = kx (y is directly proportional to x)

2 Use given values to find k

3 Substitute k back into equation

4 Use equation to find unknown values

5 Example: If y ∝ x and y = 12 when x = 3, find k = 12/3 = 4, so y = 4x

Keep building this topic

Read this section alongside the surrounding pages in Proportion. That gives you the full topic sequence instead of a single isolated revision point.

Types of Proportion Method: Inverse Proportion The Language of Relationships What is Proportion?

Practice Questions for Proportion

y is directly proportional to x. Which equation could represent this relationship?

A. y = k/x
B. y = kx
C. y = k − x
D. y = x²

1 markfoundation

Explain how you can tell from a graph whether two quantities are in direct or inverse proportion.

2 marksstandard

Quick Recall Flashcards

Recipe Application

Recipe for 4 people uses 300g flour How much for 10 people? Flour ∝ People (direct) F = kP 300 = k × 4, so k = 75 For 10 people: F = 75 × 10 = 750g

Proportion Symbol

∝ means 'proportional to' Examples: y ∝ x (y is proportional to x) y ∝ 1/x (y is inversely proportional to x)

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Types of Proportion

Method: Inverse Proportion