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NumberStudy Notes

Worked Example 4: Speed and Time

Part of Proportion — GCSE Mathematics

This study notes covers Worked Example 4: Speed and Time 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 10 of 15 in this topic. Use this study notes to connect the idea to the wider topic before moving on to questions and flashcards.

Topic position

Section 10 of 15

Practice

12 questions

Recall

22 flashcards

Worked Example 4: Speed and Time

For a journey of fixed distance, time is inversely proportional to speed. At 60 mph, the journey takes 2 hours. How long at 40 mph?

Solution

T ∝ 1/S, so T = k/S

When S = 60, T = 2: 2 = k/60

k = 2 × 60 = 120

So T = 120/S

When S = 40: T = 120/40 = 3

Answer: 3 hours

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.

Worked Example 3: Recipe ScalingWorked Example 5: Square RelationshipsThe Language of RelationshipsWhat 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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Worked Example 3: Recipe Scaling

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Worked Example 5: Square Relationships