Ratio & ProportionStudy Notes
Worked Example 2 (Higher): Proportional to Square
Part of Proportion Graphs — GCSE Mathematics
This study notes covers Worked Example 2 (Higher): Proportional to Square 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 5 of 5 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 5 of 5
Practice
14 questions
Recall
4 flashcards
Worked Example 2 (Higher): Proportional to Square
y is directly proportional to x². When x = 3, y = 45. Find y when x = 5.
Step 1 Set up the equation
y ∝ x² means y = kx²
Step 2 Find k
45 = k × 3² = k × 9
k = 45 ÷ 9 = 5
Step 3 Find y when x = 5
y = 5 × 5² = 5 × 25 = 125