Population Pyramids (Edexcel GCSE Statistics): Revision Note

• Be aware of rounding when answering population pyramid questions

  • For example rounding all percentages to 1 decimal place might mean the percentages don't add up to exactly 100%

  • Or a percentage might be given as 0.0% even though there are some people in that group

    • But if the actual percentage is less than 0.05% it will round to 0.0% to 1 decimal place

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

This shows that Lisa's claim is justified

Lisa's claim is justified, because other numbers will also be equal to 3.3% of 154064 if you round to 1 decimal place. For example 5090 people would also round to 3.3% to 1 decimal place.

Homer is carrying out research into the ages of people in Springborough. He uses the information in the population pyramid to claim,

                         "In Springborough in 2023 the number of females who were
                         40 or older was greater than the number of males who were
                         40 or older."

(d) Explain whether or not Homer's claim is correct.

The easiest way to show that Homer is incorrect is just to notice that all the bars from 40-49 and upwards are higher for males than for females

Homer's claim is not correct. From the age of 40 upwards, each year group in the population has a greater percentage of males than females, so it it is actually the number of males 40 and over which is greater.

You could also do this by adding up the figures next to the bars to show that 18.0% of the population is female and over 40, but 20.4% of the population is male and over 40