In this section we revise collecting data to produce vertical line graphs or pie charts.
3  7  6  2  5  9  10  8  7  1 
8  4  3  5  6  7  8  7  6  5 
3  6  9  8  7  5  9  6  7  8 
Step 1: Produce a frequency table:
This is a table showing the number of times each score appears.
For example, the score "5" appears 4 times, so the frequency of "5" is 4.
You can also use a tally when counting up the frequency of each item.
Step 2: Work out the angles for the pie chart:
There are 360° round a circle, and 30 pupils in the class.
To work out the angle for each pupil, you need to divide 360° by 30.
The angle for 1 pupil is 12°.
To work out the angle for a particular score, you need to multiply the number of pupils who got that score by 12°.
For example, the angle for the score "5" will be 48° because the frequency of "5" is 4, and 4×12° = 48°.
The workings for this example are shown in the table below:
Score  Frequency  
1 × 12° = 12°  
1 × 12° = 12°  
3 × 12° = 36°  
1 × 12° = 12°  
4 × 12° = 48°  
5 × 12° = 60°  
6 × 12° = 72°  
5 × 12° = 60°  
3 × 12° = 36°  
1 × 12° = 12°  
Totals 
It's a good idea to check that your angles add up to 360°.
Step 3: Draw and label the pie chart:
Start with a circle, and draw a line from the centre to the top.
Then mark off each angle around the circle, and label the "pieces" of the "pie".
Don't forget to give the pie chart a title.
The final result should look like this:
Step 4: Draw the vertical line graph:
In a vertical line graph, the frequency always goes on the vertical axis.
The scores will be on the horizontal axis and there will be one vertical bar for each score.
The height of each score's vertical bar is given by the frequency of that score.
Don't forget to label both axes and give the graph a title.
The final result should look like this:
Practice Questions
Work out the answer to each of these questions then click on the button marked
to see whether you are correct.
(a) Use the pie chart to complete this sentence: "Half the class scored more than ____ marks."
(b) Use the bar chart to work out which score occured the most often.


