Ratio & ProportionDeep Dive

Method: Finding the Constant

Part of Proportion Graphs — GCSE Mathematics

This deep dive covers Method: Finding the Constant within Proportion Graphs for GCSE Mathematics. Revise Proportion Graphs in Ratio & Proportion for GCSE Mathematics with 14 exam-style questions and 4 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 3 of 5 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 3 of 5

Practice

14 questions

Recall

4 flashcards

Method: Finding the Constant

1 Write the equation: y = kx (or y = kx² for Higher)

2 Substitute given values to find k

3 Rewrite formula with the k value

4 Use your formula to find missing values

Keep building this topic

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

Key Facts Worked Example 1: Basic Direct Proportion What Is Direct Proportion?Worked Example 2 (Higher): Proportional to Square

Practice Questions for Proportion Graphs

Which of the following describes the graph of a direct proportion relationship?

A. A curved line passing through the origin
B. A straight line passing through the origin
C. A straight line that crosses the y-axis above zero
D. A U-shaped curve symmetric about the y-axis

1 markfoundation

Aisha says: 'Because the graph of y against x is a straight line, y must be directly proportional to x.' Is Aisha correct? Explain your answer.

2 marksstandard

Quick Recall Flashcards

Finding k

Use given values to find constant k, then apply to new values

Direct vs Inverse

Direct: both increase together (y ∝ x). Inverse: one increases, other decreases (y ∝ 1/x).

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Key Facts

Worked Example 1: Basic Direct Proportion