The document discusses ratios and provides examples of how to use ratios to calculate quantities. It explains that a ratio shows a relationship between quantities and can be used to scale up or down amounts. Examples include baking a cake according to ingredient ratios and calculating the number of ducks in a pond given the ratio of geese to ducks. It also demonstrates how to scale recipe amounts for different numbers of people using ratios.

1. October 4, 2012
Ratio
2. Sharing a quantity according to a ratio.
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2. Explanation October 4, 2012
To make a basic cake, you need to mix the ingredients in the ratio:
3 parts flour, 2 parts sugar, 2 parts butter and 1 part eggs.
: : :
You need to bake an 800g cake.
Add together all of the numbers in the ratio. 3 +2+2+1 = 8
Divide the target weight by this total. 800g ÷ 8 = 100g
Multiply your answer by each number in the ratio.
3 × 100g = 300g flour
2 × 100g = 200g sugar
2 × 100g = 200g butter
1 × 100g = 100g eggs
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3. Example October 4, 2012
A pond containing geese and ducks has 32 birds in total. There
are more geese than ducks in a ratio of 5:3. How many ducks are
there?
5+3= 8 32 ÷ 8 = 4 4 × 3 = 12
There are 12 ducks in the pond.
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4. Example October 4, 2012
This is a recipe for a fruit drink for six people.
300g chopped oranges
1500ml lemonade
750ml orange juice
How much lemonade do you need to make enough drink for 9
people and for 10 people?
You can quickly find the answers here, by dividing the
quantity of lemonade used by 6, then multiplying your
answer by the new target quantities.
1500ml ÷ 6 = 25ml
9 × 25ml = 225ml
10 × 25ml = 250ml
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