GCSE Maths Revision Guide
Direct & Inverse Proportion
Solve problems involving y ∝ x and y ∝ 1/x. This free GCSE Maths module combines short explanations, worked examples, flashcard-style recall, and timed practice so students can revise the topic without creating an account.
Foundation Skills
Direct Proportion
One value increases at the same rate as the other. y = kx.
Example: 5 apples cost £1, so 10 apples cost £2.
Inverse Proportion
As one value increases, the other DECREASES. y = k/x.
Example: More builders on a job = less time taken.
Higher Skills
Proportion with Powers
y can be proportional to x², x³ or √x.
Formula: y = kx²
Example: Area of circle ∝ r²
Finding k
Substitute values of x and y to find the constant of proportionality (k), then rewrite the formula.