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Best Buy Questions

To work out which offer/product offers the best value for money we need to either compare:
• the price for the same amount of the product
• or how much of the product you get for the same amount of money

We need to either make the amount the same or the price the same.


Example: Tea bags are available in the supermarket in small packs or large packs.

**Small packs: 160 tea bags for £2.50

Large packs: 240 tea bags for £4

**Which pack offers better value for money?


We can either make the number of tea bags the same or the price the same


To make the number of tea bags the same we need to find a common factor, or a common multiple, of 160 and 240

480 is a common multiple of 160 and 240

We can compare the price of 480 tea bags by buying 3 small packs and 2 large packs

160 × 3 = 480
£2.50 × 3 = £7.50
3 small packs gives us 480 tea bags for £7.50

240 × 2 = 480
£4 × 2 = £8
2 large packs gives us 480 tea bags for £8

£7.50 < £8
The small pack offers better value for money


To make the price the same we need to find a common factor, or a common multiple, 2.5 and 4

20 is a common multiple of 2.5 and 4

We can work out how many tea bags we would get for £20
We need to multiply the small pack by 8 and the large pack by 5

160 × 8 = 1280
£2.50 × 8 = £20
With the small packs we get 1280 tea bags for £20

240 × 5 = 1200
£4 × 5 = £20
With the large packs we get 1200 tea bags for £20

1280 tea bags > 1200 tea bags
The small pack offers better value for money


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Lesson

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Flowchart comparing 12 rolls for £4.20 and 5 rolls for £1.85, converting to pence, finding 35p and 37p per roll, and choosing the lower unit cost

Best buy questions ask which option gives the best value for money. To compare fairly, turn each option into the same unit, such as p per roll, p per kg, or p per 100 ml.

The best value is the option with the lowest unit cost, not always the lowest total price. A smaller pack often costs less overall but more for each item.

A useful formula is

unit cost=total pricequantity \text{unit cost} = \frac{\text{total price}}{\text{quantity}} unit cost=quantitytotal price​

If prices are in pounds, converting to pence first often makes the calculation easier.

Questions

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24 exam-style questions

Practice questions

Question 1

3 marks

Two packs of toilet rolls are available in the supermarket

9 toilet rolls for £3.15£3.15£3.15

4 toilet rolls for £1.36 £1.36\,£1.36

Work out which pack offers the best value for money.
You must show your working.

Flashcards

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24 flashcards

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In a best-buy question, what must you compare between different pack sizes?

Best Buy Questions Revision Guide

  1. GCSE
  2. /Maths
  3. /Best Buy Questions

Revision notes for Edexcel GCSE Maths Best Buy Questions. Open the guide for explanations and worked examples. Written against the Edexcel GCSE Maths (1MA1) specification, so the content matches what's examinable rather than general Maths background.

Revision guides

Practise questions

1 of 8

A 500 ml bottle costs £1.45 and a 750 ml bottle costs £2.10. Which bottle offers better value?