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.

Worked Example 3: Best Buy Problem

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)

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

Worked Example 3: Best Buy Problem

Practice questions for Direct Proportion

Quick recall flashcards

15 questions on Direct Proportion — practise free