Shop A: 5 apples for £1.20. Shop B: 8 apples for £2.00. Which is better value?

Step 1 Find price per apple at each shop

Shop A: £1.20 ÷ 5 = £0.24 per apple

Shop B: £2.00 ÷ 8 = £0.25 per apple

Step 2 Compare

Shop A is better value (cheaper per apple)

This study notes covers Worked Example 3: Best Buy Problem within Direct Proportion for GCSE Mathematics. Revise Direct Proportion in Ratio & Proportion for GCSE Mathematics with 15 exam-style questions and 12 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 7 of 9 in this topic. Use this study notes to connect the idea to the wider topic before moving on to questions and flashcards.

Practice questions for Direct Proportion

Which of the following correctly reads the mathematical statement y ∝ x?

A. y is inversely proportional to x
B. y is directly proportional to x
C. y equals x
D. y is greater than x

1 markfoundation

Explain what it means for y to be directly proportional to x. Your answer should refer to the equation and the graph.

2 marksstandard

Quick recall flashcards

What does the symbol ∝ mean?

'is proportional to' y ∝ x means 'y is proportional to x' This is equivalent to writing y = kx for some constant k.

What does the graph of y = kx look like?

A straight line passing through the origin (0, 0). The gradient of the line equals k. If the line does NOT pass through (0,0), it is NOT direct proportion.

Worked Example 3: Best Buy Problem

Practice questions for Direct Proportion

Quick recall flashcards

15 questions on Direct Proportion: practise free