Key Stage 3 Ratio and Proportion

Percentages

Solve percentage increase, decrease, original value and simple interest problems.

Key idea

Find the multiplier or unit amount, then apply the same proportional change to the value you need.

What you will learn

Use percentage change confidently.

Use original value confidently.

Use simple interest confidently.

Use financial maths confidently.

✓I can explain what percentages means.

✓I can choose a suitable method without being told.

✓I can show clear working and check my answer.

Worked example

Model method

Step 1

There are 3 + 5 = 8 parts.

Step 2

Each part is £40 ÷ 8 = £5.

Step 3

The shares are 3 × £5 and 5 × £5.

Answer

£15 and £25

Question 1

Share £60 in the ratio 2:3.

Question 2

5 pens cost £3. Find the cost of 12 pens.

Question 3

Increase £80 by 15%.

These are linked to the wider Ratio and Proportion topic for now.

A compact Ratio and Proportion summary with key facts, methods, reminders and common mistakes.

KS3 exam-style Ratio and Proportion questions with mixed practice, marks-style prompts and model answers.