NumberDeep Dive

Advanced: Complex Proportions

Part of ProportionGCSE Mathematics

This deep dive covers Advanced: Complex Proportions 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 12 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 12 of 15

Practice

12 questions

Recall

22 flashcards

Advanced: Complex Proportions

More complex relationships include:

  • Square relationships: y ∝ x² (area problems)
  • Cube relationships: y ∝ x³ (volume problems)
  • Square root: y ∝ √x (some physics laws)
  • Combined: z ∝ xy (z proportional to product of x and y)

Key insight: The constant k gives the relationship its "strength"

If y ∝ x² and k = 3, then doubling x makes y four times bigger (×4), but also three times that due to k

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.

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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