GCSE Maths Practice: best-value

Question 8 of 10

Some milk cartons may cost exactly the same per litre. Use unit price to check carefully.

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\( \begin{array}{l} \text{Which milk cartons give the best value for money?} \end{array} \)

Select all correct options:

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

Best Value Does Not Always Mean One Answer

In many GCSE Maths best value questions, students expect there to be one single correct option. However, this is not always the case. Sometimes different products are priced in direct proportion to their size, meaning they all cost the same per unit. When this happens, every option offers the same value for money.

These questions are designed to test whether you fully understand the idea of unit pricing rather than relying on guessing or assumptions. Recognising equal value is just as important as finding the cheapest option.

Using Unit Price to Compare Value

The key method for solving best value problems is calculating the unit price. For liquids, this usually means cost per litre.

  1. Identify the unit to compare (litres).
  2. Divide the price by the number of litres for each option.
  3. Compare the results.

If the unit prices are identical, then all options are equally good value.

Worked Example

A shop sells fruit juice in the following bottles:

  • 1 litre for £1.20
  • 2 litres for £2.40
  • 4 litres for £4.80

Calculate the cost per litre:

  • £1.20 ÷ 1 = £1.20 per litre
  • £2.40 ÷ 2 = £1.20 per litre
  • £4.80 ÷ 4 = £1.20 per litre

Each bottle costs the same per litre, so none is better or worse value than the others.

Another Example

Petrol is sold as:

  • 5 litres for £7.50
  • 10 litres for £15.00
  • 20 litres for £30.00

Dividing the price by the volume in litres shows that the cost per litre is the same in each case.

Common Mistakes

  • Assuming bigger is better: A larger size is not automatically better value.
  • Choosing only one option: If unit prices match, more than one answer may be correct.
  • Skipping calculations: Always calculate the unit price, even if prices look similar.

Real-Life Applications

Supermarkets often price products proportionally so that different sizes offer equal value. This allows customers to choose based on convenience rather than cost. Understanding this helps you recognise when there is no financial advantage to buying a larger or smaller pack.

This skill is also useful when comparing fuel, bottled water, cleaning liquids, and paint.

Frequently Asked Questions

Can all options be correct in best value questions?
Yes. If the unit prices are the same, all options offer equal value.

How do I know if values are equal?
Calculate the unit price for each option and compare carefully.

Does this appear in GCSE exams?
Yes. Foundation papers sometimes include questions where multiple answers are correct.

Study Tip

If unit prices match exactly, do not look for a trick — equal value means equal answers.

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