Proportional Reasoning
Proportion: comparing quantities
Proportions are everywhere in maths, science, commerce and many other areas of life. For example you need to reason with proportions to operate successfully in:
- fractions, decimals and percentages
- scale drawings and maps
- probability
- drawing timelines
- interpreting and comparing rates such as speed, density and unit price.
What do you know about proportions?
Try these questions:
Orange paint is made by mixing red and yellow in the ratio 1:3. If I added two more parts of red, how many more parts of yellow would I need?
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Between 2003 and 2006 two trees, Tree A and Tree B, grew 3 metres. Which tree grew the most as a proportion of its original height?
| 2003 | 2006 | |
| Tree A | 2 metres | 5 metres |
| Tree B | 3 metres | 6 metres |
[ ]Tree A [ ]Tree B [ ]They grew by the same proportion
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The ratio of women to men at a concert is $3 : 4$. If there are $210$ men and women at the concert, how many women are there?
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The distance covered in an interval of time is called speed. A boy runs $1000$ metres in $500$ seconds. What is the boy’s running speed in metres per second?
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If blood flow through an artery is $0.5$ litres per second, how many litres of blood pass through the artery in $60$ seconds?
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Cereal costs $\$4$ for $500$ grams. What is the cost for $100$ grams? Give your answer in dollars.
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