Scaling with Ratios

Scaling is one of the most practical applications of ratios in QR. Whenever a recipe, formula, or pattern needs to be adjusted for a different quantity, you are scaling with ratios. This lesson covers the methods for scaling up and down, including handling non-integer scale factors.

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The Scale Factor

The scale factor tells you how much to multiply each quantity by.

Formula: Scale Factor = New Quantity ÷ Original Quantity

Example: A recipe serves 4 people. You want to serve 6.

Scale factor = 6 ÷ 4 = 1.5

Multiply every ingredient by 1.5.

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Scaling Up

Worked Example: Recipe Scaling

Data: A cake recipe for 8 servings requires:

Ingredient	Amount
Flour	400 g
Sugar	200 g
Butter	250 g
Eggs	4
Milk	300 ml

Question: What quantities are needed for 12 servings?

Step 1: Scale factor = 12 ÷ 8 = 1.5

Step 2: Multiply each ingredient by 1.5: