Fractions and percentages represent part of a whole number. They can be used to increase or decrease a value by a given proportion.
Part of Maths Numeracy (WJEC)Number
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\(\frac {2} {7}\) or 'two sevenths' means two parts out of seven.
To find \(\frac {2} {7}\) of a value, you must first divide by 7 to find what \(\frac {1} {7}\) is worth, and then multiply by 2.
To find a fraction of an amount:
Calculate \(\frac {2} {7}\) of 84.
24.
There are 30 pupils in a class. \(\frac {1} {5}\) of pupils play a musical instrument. How many do not play an instrument?
\(\frac {1} {5}\) of 30 = 30 ÷ 5 = 6 pupils play a musical instrument.
This leaves 30 – 6 = 24 pupils who do not play an instrument.
2/5 of the people on a bus are children. If there are 4 children on the bus, how many people are there in total?
\(\frac {2} {5}\) of the value = 4
Divide by 2 to find \(\frac {1} {5}\)
\(\frac {1} {5}\) of the value = 2
Multiply by 5 to find \(\frac {5} {5}\) or 1 whole
10 people in total.
I eat \(\frac {3} {8}\) of a chocolate bar and am left with 20 squares, how many squares were there to begin with?
\(\frac {3} {8}\) has been eaten, which leaves \(\frac {5} {8}\)
\(\frac {5} {8}\) = 20 squares (now divide by 5)
\(\frac {1} {8}\) = 4 squares (now multiply by 8)
1 whole = 32 squares.
Louis’ father increases his pocket money by \(\frac {1} {3}\). He now receives £26 a month. How much was he receiving originally?
£19.50
\(\text {1 whole} + \frac {1} {3} = \frac {3} {3} + \frac {1} {3} = \frac {4} {3} \)
\(\frac {4} {3}\) = £26 (now divide by 4)
\(\frac {1} {3}\) = £6.50 (now multiply by 3)
1 whole = £19.50