Wednesday, 7 January 2009

Ratio, Proportion, Scale

There are usually 2 if not 3 questions on both Level 1 and Level 2 Numeracy papers; this is then a crucial skill.

1. Understand that ratios can be simplified in the same way as fractions.
2. Use ratios directly to find 'parts' in a drink, a mix of cement etc.
3. Use 'recipes' or 'menus' to convert amounts given for 4 people to 6, 8, etc.
4. To understand that the scale on a map is a ratio - to convert from the map to real life and backwards.

1. A worksheet showing how to cancel fractions will be given.

2. Ratio is given
A boy mixes a drink one part of squash to three parts of water. How much squash will he need for 2 litres of the drink?

a. Draw a bottle - label the two different components
You have
1 part of squash
3 parts of water
4 parts altogether

b. Find out what each part is worth
Divide 2 litres by 4
Change 2 litres into 2000 millilitres

c. The answer is 1 part is worth 2000/4 = 500ml

d. Draw in your diagram squash =500ml (1 part), water =1500ml (3 parts)

The Skillwise worksheets help.

Watch CBS Videos Online
3. A menu is given
e.g. 200g of sugar is used in a recipe for 12 cakes. How much sugar will be needed for 60 cakes?

a. The ratio is 12:60 or 1:5 so multiply by 5
b. 5x200g = 100g
c. Convert to kg, so the answer is 1kg

4. A Scale on a map is given

e.g. A map has a ratio of 1cm = 5m. How will 12.5m be displayed on the map?

a. The ratio is 1:5 so divide by 5 (converting back)
b. 12.5/5 = 2.5
c. Write in the correct units 2.5cm
The OS has a good site