Ratio, proportion and rates of changeKS3 / GCSE

Scaling a recipe

Adjust every ingredient for a different number of people.

  • Divide the new number of servings by the original number.
  • Multiply every ingredient by that same scale factor.
  • A smaller recipe uses a scale factor below 1.

Example 1

A recipe for people uses of flour, of milk and of sugar. Find the amounts for people.

Scale every ingredient by the same factor.

Ingredient people people
Flour
Milk
Sugar
New servings ÷ original servings gives the scale factor.
Flour Milk Sugar

Example 2

A recipe for people uses of flour, of milk and of sugar. Find the amounts for people.

Scale every ingredient by the same factor.

Ingredient people people
Flour
Milk
Sugar
New servings ÷ original servings gives the scale factor.
Flour Milk Sugar

Remember
A smaller recipe uses a scale factor below 1.

Your turn

Question 1

A recipe for people uses of flour, of milk and of sugar. Find the amounts for people.

Check answer

Scale every ingredient by the same factor.

Ingredient people people
Flour
Milk
Sugar
New servings ÷ original servings gives the scale factor.
Flour Milk Sugar
Question 2

A recipe for people uses of flour, of milk and of sugar. Find the amounts for people.

Check answer

Scale every ingredient by the same factor.

Ingredient people people
Flour
Milk
Sugar
New servings ÷ original servings gives the scale factor.
Flour Milk Sugar
Question 3

A recipe for people uses of flour, of milk and of sugar. Find the amounts for people.

Check answer

Scale every ingredient by the same factor.

Ingredient people people
Flour
Milk
Sugar
New servings ÷ original servings gives the scale factor.
Flour Milk Sugar
Question 4

A recipe for people uses of flour, of milk and of sugar. Find the amounts for people.

Check answer

Scale every ingredient by the same factor.

Ingredient people people
Flour
Milk
Sugar
New servings ÷ original servings gives the scale factor.
Flour Milk Sugar
Question 5

A recipe for people uses of flour, of milk and of sugar. Find the amounts for people.

Check answer

Scale every ingredient by the same factor.

Ingredient people people
Flour
Milk
Sugar
New servings ÷ original servings gives the scale factor.
Flour Milk Sugar
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