18.06 Pictograms and bar charts
Bar charts
A bar chart is a graph used to display relative quantities of data in different categories. There is a wide range of topics where this type of graph can be useful. For example the number of tourists visiting different destinations in a month, the number of people with certain eye colours in a class or the popularity of the top ten YouTube channels.
| Eye colour in a class |
|---|
 |
- Title the graph clearly
- Label each axis
- Label each category and give the vertical axis a clear scale
- Make sure the columns are equal widths and equally spaced
- Make sure that the height of the column matches the value it represents which is often the frequency of the category (how often that outcome occurred)
Practice questions
Question 1
Here is a graph of students’ eye colors in Miss Skye’s class.
Which eye colour was most common?
blue
Agreen
Bblack
Cbrown
DHow many more students had green eyes than brown eyes?
Which eye colour do $3$3 students have?
brown
Ablack
Bblue
Cgreen
D
Pictograms
A pictogram is very similar to a bar chart in that is displays the relative size of data in different categories. It differs by using using pictures or symbols to represent data rather than a column. Pictograms have a key, which explains what each symbol represents.
For example the following pictogram displays the number of glasses of water $6$6 students drank in a week. In this case, each glass represents $6$6 glasses of water, thus, we can see that Conrad consumed $5.5\times6=33$5.5×6=33 glasses of water.
Practice questions
Question 2
It’s "Back to school" time and a shop recorded the number of pens they sold this week.
| Day | Number of pens sold |
|---|---|
| Monday |  |
| Tuesday | |
| Wednesday | |
| Thursday | |
| Friday | |
| Saturday | |
| Sunday | |
Where represents $5$5 pens.
How many pens were sold on Wednesday?
How many more pens were sold on Saturday than on Wednesday?
Question 3
A survey was conducted asking students what transport they used to get to school.
The pictograph shows the responses.
What form of transport is used by exactly $18$18 people?
Train
ABus
BCar
CWalk
DBike
EWhat is the difference between the amount of students who use the most common form of transport and the amount of students who use the least common form of transport?
How many people participated in the survey who don't catch the train to school?