# Population Density

## Population Density Revision

**Population Density**

**Population density** tells us how many people are living in a given location. It is often given in people per \text{km}^2, which means in an area, approximately how many people live in each \text{km}^2

**Calculating Population Density**

To calculate **population density**, you need to know the **population** of an area and the **size** of an area.

The equation for **population density** is:

\text{Population density} = \dfrac{\text{Population}}{\text{Land Area}}

If somewhere is crowded, it will have a high population density, and if somewhere is sparsely populated, it will have a low population density.

**Example 1: Calculating Population Density**

Calculate the **population density** of Boston given that it has a population of 650000 and an area of 230\text{ km}^2.

**[2 marks]**

To calculate this, we will use the equation.

\text{Population density} = \dfrac{\text{Population}}{\text{Land Area}}

\text{Population density} = \dfrac{650000}{230}

\text{Population density} = 2826\text{ people}/\text{km}^2 to the nearest whole number.

**Example 2: Using the Equation**

San Francisco has a population density of 1350\text{ people}/\text{km}^2 and a population of 810000.

Work out the area of San Francisco.

**[3 marks]**

We will use the equation again, but will have to rearrange it:

\text{Population density} = \dfrac{\text{Population}}{\text{Land Area}}

1350 = \dfrac{810000}{\text{Land Area}}

Rearrange:

\text{Land Area} = \dfrac{810000}{1350}

\text{Land Area} = 600\text{ km}^2

## Population Density Example Questions

**Question 1**: York has an area of 270\text{ km}^2 and a population of 210000

Work out the population density of York to the nearest whole number.

**[2 marks]**

**Question 2**: Birmingham has a population of 1.2\text{ million} and a size of 270\text { km}^2 whereas Manchester has a population of 500000 and an area of 115\text{ km}^2.

Work out which area has a higher population density.

**[4 marks]**

Birmingham:

Population density = 1200000\div270\\

Population density =4444\text{ people}/\text{km}^2

Manchester:

Population density = 500000\div115\\

Population density =4347\text{ people}/\text{km}^2

Therefore, Birmingham has a higher population density.

**Question 3:** The population density of Liverpool is 4546\text{ people}/\text{km}^2, and the area is 110\text{ km}^2. Work out the population of Liverpool.

**[2 marks]**

Put the figures we know into the equation:

4546=\dfrac{\text{Population size}}{110}Rearrange:

\text{Population size}=4546\times110\text{Population size}=500060

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