What you need to know
To achieve 100 you need to:
use simple ratio to compare quantities
estimate the distance on a map using a simple scale.
- Ratio is the relationship between two or more quantities. It compares ‘part with part’, e.g. the ratio 3:1 means 3 for every 1.
- Proportion is the relationship between part of something and the whole thing. It compares 'part with whole', e.g. 1 out of 4 is the same as 2 out of 8. Think of proportion as a fraction,
= 
. We can also write this proportion as 0.25 or 25%.