What is proportion?
A proportion is when two ratios are equal. If things stay in the same ratio, we say they are in proportion. When one amount goes up, the other goes up in the same way. For example, if 1 pen costs RM3, then 2 pens cost RM6 and 3 pens cost RM9 — the cost grows in step with the number of pens.
Key idea
To solve a proportion, first find the value of ONE unit (the "unitary method"), then multiply. For example: cost of 1 item = total cost ÷ number of items.
Using the unit
Once you know the value of one, you can find the value of any number of them by multiplying.
Worked example
2 pens cost RM6. What do 5 pens cost?
Cost of 1 pen = RM6 ÷ 2 = RM3.
Cost of 5 pens = 5 × RM3 = RM15.
Remember
- Find the value of ONE first, then multiply.
- More items → more cost (they change together).
- Check the units match (RM, km, cups).