Exam mix: ratio and proportion

2026-12-17Exam & Challenge Mr Chan

Share ratios and decide direct versus inverse proportion quickly.

Key formulas

y=\text{kx or xy}=k

What this lesson covers

This lesson builds Secondary 2–3 skill in exam ratio proportion. Read the key formulas, study the worked example, then attempt the written practice and the four-question MCQ review.

Method

Write every step. Name the rule you use (exam ratio proportion) before substituting numbers. Keep units and signs visible until the final sentence.

Common mistakes

Students often rush the sign, use the wrong percentage base, or cancel terms instead of factors. Pause after each line and ask whether the step is reversible.

Exam habit

Underline the question verb (simplify, solve, factorise, find). Box the final answer and, where sensible, substitute back for a quick check.

Worked example

Worked example — exam ratio proportion

Problem. Apply the method for exam ratio proportion with the numbers 7 and 4.

Solution. Identify the rule for exam ratio proportion. Substitute 7 and 4 carefully with signs in brackets if needed. Complete each operation on a new line. State the final answer clearly and check by reversing one step.

Review quiz

1 / 4

Warm-up on exam ratio proportion: what is 6+2?

Practice questions

Practice 1 on exam ratio proportion: compute with the value 15.
Practice 2 on exam ratio proportion: change the numbers and repeat the same method.
Practice 3 on exam ratio proportion: write one sentence explaining the key rule.
Practice 4 on exam ratio proportion: invent a similar exam-style question and solve it.

Study notes

What is the main idea of exam ratio proportion?

Apply the stated formula or rule with clear steps, then check by reversing or substituting.

How should I revise this topic?

Cover the worked example, redo the practice without notes, then complete the MCQ set and log any wrong options.