Exam code:1ST0
Population Pyramids
What is a population pyramid?
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A population pyramid is a diagram that shows how a population is distributed between different age groups
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It is similar to a bar chart or a stem and leaf diagram
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The population is usually divided by gender (female/male) as well
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Each horizontal bar represents the part of the population belonging to that age group
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The horizontal scale will sometimes show the actual number of people (i.e. the frequency)
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But most often it will show the percentage of the population instead
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This might be percentage of the total population
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Or when split by gender it might only be percentage of the respective female or male populations
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Read the question closely to see which percentage is being used
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It is possible that you will be given two population pyramids for different populations
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In this case you will be expected to make comparisons between the info about the two populations
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Examiner Tips and Tricks
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Be aware of rounding when answering population pyramid questions
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For example rounding all percentages to 1 decimal place might mean the percentages don’t add up to exactly 100%
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Or a percentage might be given as 0.0% even though there are some people in that group
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But if the actual percentage is less than 0.05% it will round to 0.0% to 1 decimal place
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Worked Example
The population pyramid gives information about the percentages of the population of the city of Springborough who are male and who are female in each age group in 2023.
Each percentage is given correct to 1 decimal place.

(a) Write down the percentage of the population who are male in the age group 40-49.
This is the ‘8.0%’ bar on the right side of the diagram
8.0%
(b) Work out the percentage of the population who are female in the age group 0-19.
Add together the percentages on the ‘female’ bars for 0-9 and 10-19
12.8%
To the nearest whole number, 3.3% of 154064 is 5084.
Bartholomew claims that this must be the number of females in the 60-69 age group in Springborough.
Lisa claims that the exact number might be different from this.
(c) Explain with a reason whether or not Lisa’s claim is justified.
The question says that the percentages are rounded to 1 decimal place
Other numbers besides 5084 are probably also equal to 3.3% of 154064 when you round to 1 decimal place
Test another number close to 5084
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