RATIO AND PROPORTION

Scaling Recipes

Learn the reliable method for scaling recipes, then apply it to 11+ exam-style questions.

1 · WHAT YOU NEED TO KNOW

The idea

Direct proportion keeps the amount per one unit constant.

Picture itCount equal parts of one whole
Bowls, fruit, scales and a measuring jug showing ratio and measurement in baking
2 · THE METHOD

Follow these steps

  1. Find the value for one unit.
  2. Multiply by the number of units required.
  3. Include the correct unit and check that both quantities scale in the same direction.
one share = total ÷ sum of ratio parts
3 · WORKED EXAMPLES

See the method in action

Example 1

8 people use 320 ml of oil. How much is needed for 18 people at the same rate?

  1. First find one unit: 320 ÷ 8 = 40.
  2. Then scale: 40 × 18 = 720.
Answer: 720 ml
Example 2

6 people use 450 g of rice. The amount for 18 people is prepared, but 150 g is set aside. How much remains?

  1. First find one unit: 450 ÷ 6 = 75.
  2. Then scale: 75 × 18 = 1350, and subtract 150 to get 1200.
Answer: 1200 g
4 · ELEVENSPRINT TIP

A useful shortcut

Include the correct unit and check that both quantities scale in the same direction.

5 · COMMON MISTAKES

Watch out for these

6 · TRY IT YOURSELF

Three fresh questions

Ready to check the method? You will get three fresh, validated questions.