Shampoo bottles (300ml each): Normal price £3.50. Offer A: 20% off. Offer B: Buy 2 get 1 free. Which is better for buying 3 bottles?
Step 1 Calculate Offer A (20% discount)
20% off £3.50 = £3.50 × 0.8 = £2.80 per bottle
3 bottles = 3 × £2.80 = £8.40
Price per ml = £8.40 ÷ (3 × 300ml) = £0.0093 per ml
Step 2 Calculate Offer B (buy 2 get 1 free)
Pay for 2 bottles, get 3 bottles
Cost = 2 × £3.50 = £7.00
Price per ml = £7.00 ÷ (3 × 300ml) = £0.0078 per ml
Final Compare offers
£0.0078 per ml < £0.0093 per ml
Buy 2 get 1 free is better value
This study notes covers Worked Example 3: Percentage Discount vs Multi-Buy within Best Buy for GCSE Mathematics. Revise Best Buy in Ratio & Proportion for GCSE Mathematics with 12 exam-style questions and 22 flashcards. Use this page as part of a wider topic revision path rather than treating it as an isolated fact. It is section 6 of 8 in this topic. Use this study notes to connect the idea to the wider topic before moving on to questions and flashcards.
Practice questions for Best Buy
Which method correctly compares the value of two products?
Three sizes of shampoo are available: - Travel: 100 ml for 95p - Regular: 300 ml for £2.55 - Family: 500 ml for £4.00 Find the best value size. Show all working.