Key Stage 3 Ratio and Proportion

Currency and Best Buys

Use unit pricing, exchange rates and comparison methods in practical contexts.

Key idea

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

What you will learn

Use unit price confidently.

Use best buys confidently.

Use exchange rates confidently.

Use comparison confidently.

✓I can explain what currency and best buys 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.