A proportion is used to describe how a part relates to a whole.
A ratio relates how parts are related to each other.
This can be shown operating as fractions. If £20 was split in the ratio 7:13 then the fractions are:
`frac(7)(20)` and `frac(13)(20)`
with the ratios being a comparison of the numerators (7:13), and the proportions being the numerator and the denominator.
A road crew has relaid part of a new road with fresh tarmac. They completed 6km in 6 days. A second road crew has become available. If both road crews can work at the same time, how long should it take to complete 10km?
It takes a road crew 1 day to lay 1km.
Two road crews should complete 2km per day.
10km ÷ 2 = 5 days
Answer: 5 days
A prize draw distributes first, second and third place prizes in the ratio 5:3:2. What proportion of the prize money does the first place winner receive? Show the proportion as a fraction.
Total of the ratios is 5 + 3 + 2 = 10
First place gets 5 out of 10, or `frac(1)(2)`
Answer: `frac(1)(2)`
See also Ratio of a Quantity