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Proportional Division Using Fractions
Examples 1 to 3 above are repeated here to show the slightly ‘simpler’ method
based on fractions. It is really the same as the method of one but presented
using the language of fractions. By using fractions there is less written
explanation.
Example 1 Repeated Using Fractions
Divide £500 in the ratio 2:3 . The explanation below is broken into 4 separate
stages. In practice you need only write out the equations shown in stages 2 and
3.
1.
Add the numbers in the ratio to find the total number of parts:
2 + 3 = 5
2.
The 2 parts is two-fifths so work out
2
5
of £500
2 parts is
2
5
× £500 = £200
3.
The 3 parts is three-fifths so work out
3
5
of £500
3 parts is
3
5
× £500 = £300
4.
Check (optional) that the resulting amounts add up to the given total:
£200 + £300 = £500
Example 2 Repeated Using Fractions
A line that is 30cm long is to be divided into 3 amounts in the ratio 2:3:5. Find
the length of the longest.
1.
Add the numbers in the ratio to find the total number of parts:
2 + 3 +5 =10
2.
Work out
5
10
of 30cm (for the longest):
The longest is
5
10
× 30 = 15cm
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