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Recipes

FoundationChallengeAQAEdexcelOCR

Master recipes for GCSE Maths with structured, exam-style practice. This Foundation resource covers scaling recipes using ratio and includes a complete mark scheme showing the steps examiners reward. Suitable for AQA, Edexcel and OCR. Free to download as a PDF. Scale every ingredient by the same factor.

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These worksheets and mark schemes are original, written for Virtus Academy and checked against the current AQA, Edexcel and OCR specifications. Every worksheet comes with a full mark scheme.

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Topic overview

Recipe questions are proportion problems in a practical setting. A recipe lists quantities for a set number of people, and you scale them up or down for a different number.

The method is to find the scale factor by dividing the new number of people by the original, then multiply every ingredient by it. Halving, doubling and trebling are just simple scale factors.

Some questions reverse this and ask how many portions you can make with limited ingredients. Work out how many times each ingredient goes in, then take the smallest answer — that ingredient is the one that runs out first and limits the total.

Revision notes

Scaling a recipe

Divide the new number of servings by the original to find the scale factor, then multiply every ingredient.

A recipe for \(4\) scaled to \(6\) has a scale factor of \(1.5\), so \(200\)g of flour becomes \(300\)g.

Using the unitary method

Divide by the original number of servings to find the amount for one person, then multiply by the number wanted.

This is often easier with awkward numbers, and it makes the working clear for method marks.

Limited ingredients

Divide each available amount by the amount needed per batch, then take the smallest result.

If you have enough flour for \(5\) batches but enough eggs for only \(3\), you can make \(3\) batches. The eggs are the limiting ingredient.

Key points

  • Find the scale factor by dividing new by original.
  • Multiply every ingredient by the same factor.
  • The unitary method finds the amount for one person first.
  • For limited ingredients, divide each by the amount needed.
  • The smallest result limits how much you can make.
  • Keep the units the same throughout.

Worked examples

Example 1

A recipe for \(4\) people uses \(120\)g of butter. How much for \(6\) people?

Working

\[6 \div 4 = 1.5\]find the scale factor
\[120 \times 1.5\]multiply the quantity
\[= 180\text{g}\]state the answer

Example 2

A recipe for \(8\) uses \(500\)ml of milk. How much for \(3\) people?

Working

\[500 \div 8 = 62.5\text{ml}\]find the amount for one person
\[62.5 \times 3\]multiply by the number wanted
\[= 187.5\text{ml}\]state the answer

Example 3

A batch needs \(4\) eggs and \(300\)g of flour. You have \(14\) eggs and \(1200\)g of flour. How many batches?

Working

\[14 \div 4 = 3.5\]find how many batches the eggs allow
\[1200 \div 300 = 4\]find how many the flour allows
\[3 \text{ batches}\]take the smaller, rounded down to a whole batch

Common mistakes

  • Scaling only some ingredients.

    Every ingredient must be multiplied by the same scale factor.

  • Taking the largest result in a limiting question.

    The ingredient that runs out first sets the limit, so take the smallest.

  • Rounding a batch count up.

    You cannot make part of a batch, so round down.

  • Mixing units.

    Convert grams and kilograms to one unit before comparing.

Exam tips

  • Write the scale factor down before scaling anything.
  • Use the unitary method when the numbers are awkward.
  • For limiting questions, check every ingredient and take the smallest.
  • Round batch numbers down, never up.

Key terms

Scale factor
The multiplier used to change quantities.
Unitary method
Finding the value of one unit first.
Limiting ingredient
The ingredient that runs out first.
Batch
One complete set of the recipe.

Related topics

Written and reviewed against the current AQA, Edexcel and OCR specifications. Spotted an error? Let us know.