GCSE Maths Practice: best-value

Question 8 of 10

Olive oil is sold in different bottle sizes. Compare the cost per litre carefully.

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\( \begin{array}{l} \text{Which olive oil bottles give the best value for money?} \end{array} \)

Select all correct options:

If the unit prices are equal, the products offer the same value.

Higher GCSE Best Value with Equal Unit Prices

At Higher tier GCSE Maths, best value questions are not always about finding a single cheapest option. In some cases, two or more products are priced in exact proportion to their size. When this happens, the products offer equal value, even though their total prices and volumes are different.

This type of question is designed to test whether students genuinely understand unit pricing. Many learners expect that either the smallest or largest bottle must be the best value, but this assumption is unreliable. The only correct approach is to calculate the unit price and compare results carefully.

The Core Method: Cost per Litre

For liquid products, the standard unit of comparison is the cost per litre.

  1. Convert all volumes into litres.
  2. Divide the total price by the number of litres.
  3. Compare the unit prices.

If two or more options have the same cost per litre, they offer equal value for money.

Worked Example

A supermarket sells sunflower oil in the following bottles:

  • 500 ml for £2.20
  • 1 litre for £4.40
  • 2 litres for £8.80

Convert volumes to litres and calculate cost per litre:

  • £2.20 ÷ 0.5 = £4.40 per litre
  • £4.40 ÷ 1 = £4.40 per litre
  • £8.80 ÷ 2 = £4.40 per litre

All bottles cost the same per litre, so none is better value than the others.

Another Higher-Tier Example

Cleaning liquid is sold as:

  • 750 ml for £3.75
  • 1.5 litres for £7.50
  • 3 litres for £15.00

Each option gives the same cost per litre, even though the prices increase significantly.

Common Higher-Tier Mistakes

  • Assuming larger bottles are better value: Bigger does not automatically mean cheaper per unit.
  • Choosing only one answer: Equal unit prices mean multiple answers may be correct.
  • Skipping calculations: Visual judgement alone is unreliable.

Real-Life Applications

Retailers often price products proportionally so customers can choose based on convenience rather than cost. For example, smaller bottles may suit occasional use, while larger bottles suit frequent use, even though both cost the same per litre.

Understanding equal value helps you avoid overthinking and recognise when there is no financial advantage to choosing a particular size.

Frequently Asked Questions

Can more than one option be correct?
Yes. If the unit prices are the same, all those options offer equal value.

Why include questions like this?
They test understanding rather than pattern guessing.

Does this appear in GCSE Higher exams?
Yes. Multiple-answer best value questions appear regularly.

Exam Tip

If unit prices match exactly, trust your calculations — equal unit cost means equal value.

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