Column and bar graphs are used to display, interpret and compare categories of data that have been counted. Bar graphs can run vertically or horizontally, but column graphs only run vertically. We can compare more than one set of data on one graph, using different colours.

We use ticksto represent the numbers between the main number points, as seen below:

Let's think about how we read this graph:

Notice how the horizontal axis says "Sales ('000)." This means that the scale is in thousands. For example, the number $4$4 represents $4000$4000 and $5$5 represents $5000$5000. The number correspond to the ticks that have vertical lines above them.

There are $5$5 ticks between the numbered lines, so to work out how much each tick is worth, we use division: $1000\div5=200$1000÷5=200, so each tick is worth $200$200.

Then we can work out the sales for each company. For example, $4200$4200 Mazdas were sold, because the graph shows it is $4000$4000 + one segment, or $200$200.

Worked Examples

Question 1

The table below shows the house points earned by four colour houses at their swimming carnival.

House

Points

Blue

$60$60

Green

$20$20

Yellow

$70$70

Orange

$60$60

Complete the graph using the information from the table.

Question 2

The sales (in thousands) of different products are shown in the following horizontal bar graph.

Which is the best-selling product?

Product A

A

Product B

B

Product C

C

Product D

D

Product E

E

Product F

F

How many units of all products were sold in total?

If product B was sold at $£50$£50 each, find the revenue generated by product B alone.

Question 3

Study the bar graph below which shows the changes in tourism rates in different cities during 2011 and 2012, then answer the following questions.

Which city had the highest percentage of tourism in 2011?

Tokyo

A

Bangkok

B

London

C

Paris

D

Which city had the lowest percentage of tourism in 2012?

Singapore

A

Shanghai

B

Rome

C

Tokyo

D

Which city had the highest percentage tourism in a single year?

London

A

Istanbul

B

New York

C

Paris

D

Which city/cities had the lowest percentage tourism in a single year?

Note: Select ALL correct answers.

Tokyo

A

Shanghai

B

Rome

C

Singapore

D

How much higher is Paris's percentage of tourism in 2011 than that of London in 2012?

20%

A

10%

B

15%

C

0%

D

Paris' maximum percentage of tourism over the 2 years is higher than Istanbul's maximum by: