How to draw a pie chart: You will need a calculator, a compass and a protractor.
• There are 360 degrees in a circle. Therefore the total of the data you want to display is equal to 360 degrees or 100 per cent.
• The first step is to work out what the total is. You do this by adding each sector. For example, the total number of pets in the pie chart above is 20.
• We now have to work out what percentage and degrees each of the sectors is: l
To get the percentage, divide each value by the total and multiply by 100. l
To get the degrees, divide each value by the total and multiply by 360. Dogs
10 Percentage Degrees
10 x 100 = 50% 20
10 x 360˚ = 180˚ 20
Cats 4
4 x 100 = 20% 20
4 x 360˚ = 72˚ 20
Fish 5
5 x 100 = 25% 20
5 x 360˚ = 90˚ 20
• Once this is done, draw a circle on your page with a compass. • Draw a line from the centre of the circle to the edge. • Measure out the angle for each sector using a protractor.
NUMERACY ACT VITY
This table shows the different ways 20 students travel to school. Look at the information below and draw a pie chart.
How students travel to school
Walk Car Bus
Cycle
6 8 4 2
No. of students
Rabbits 1
1 x 100 = 5% 20
1 x 360˚ = 18˚ 20
Total 20
100% 360˚
Trend graphs
Trend graphs show a trend or pattern for data over a period of time. They can also show the relationship between two or more sets of data.
For example, we can see the trend for energy supply and demand in the world in the trend graph on the next page. The demand for energy is going up, so the red line is increasing.
We can also see from the graph that renewable energy and fossil fuels trends are linked. The demand for renewable energy is increasing as the supply of fossil fuels is decreasing.
How to draw a trend graph: • Write a title for the graph. • Draw an x-axis and a y-axis.
• Start with the x-axis. Work out how many groups you have to show on the x-axis. For example, on this trend graph the time is measured in decades from 2000 to 2050.
