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In a family, twenty-one out of twenty-five members are female.
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What percentage of the family are female?
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Well this question is all about proportion.
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And we’ve got two common ways of representing proportion.
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The idea of a fraction represents a proportion, and the idea of a percentage also represents a proportion.
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Now in our question, it tells us that twenty-one out of the twenty-five members of the family are female.
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So the fraction that would be female is twenty-one out of twenty-five, or twenty-one over twenty-five.
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So we’ve got to find the equivalent proportion as a percentage.
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In other word, percentage could be broken down into per and cent.
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Per means out of, and cent means a hundred.
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So percentages are a number out of a hundred.
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So if I can find an equivalent fraction to twenty-one twenty-fifths, where the denominator is a hundred rather than twenty-five, then my numerator will simply be the percentage.
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And in this case, that’s relatively easy to do.
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If I multiply twenty-five by four, I get a hundred.
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So to create an equivalent fraction, I have to multiply the numerator by four as well.
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And four times twenty-one is eighty-four.
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So twenty-one over twenty-five is equivalent to eighty-four over a hundred.
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And since percentages are the amount per hundred, we’ve got an answer straightaway, that eighty-four out of a hundred.
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So the percentage is eighty-four percent.