This answer tells you how to make a pie chart physically on a paper. You can also make it digitally by following the steps upto finding out the measures of degrees and plotting those degrees in a circle drawn on a computer.
To create a pie chart you will have to first calculate your data and modify it in percentage form. Here I will be giving a stepwise example from a survey of friends which finds which kind of movie they like the best and showing you how to make a pie chart from that given data.
The given data shows no. of friends who like a given type of movie:
- Now find out the total.
- Here the total is sum of no. of friends who took part in the survey i.e. Total=4+5+6+1+4=20
- Now calculate the percentage value for each category (you calculate percentage by dividing a given value by total and multiplying by 100 with a percentage sign)
i.e. Comedy = 4 / 20 x 100 % = 20 % [ Here we divide given value (which is 4) by total value (which is 20) and multiply by 100 with a percentage sign ]
Action = 5 / 20 X 100 % = 25 %
Romance = 6 / 20 X 100 % = 30 %
Drama = 1 / 20 X 100 % = 5 %
Sci Fi = 4 / 20 X 100 % = 20 %
Now we find angles these value may later occupy in a pie chart.
- For finding angles just dividie the prcentage value by 100 and multiply by 360°.
In this case for finding the measure that Comedy category would take up in a pie chart
do : Comedy = ( 20 / 100 X 360 ) °= 72 °
Action = (25 / 100 X 360) ° = 90°
Romance = (30 / 100 X 360)° = 108°
Drama = ( 5 / 100 X 360)° = 18°
Sci Fi = (20 / 100 X 360)° = 72°
Now draw a circle with a protactor (if you are making a pie chart physically on a paper)
- Start in the exact center of the circle and draw a straight line to the outside of the circle (Hint : the center of the circle is the hole which the compass makes in the paper)
- Make a sector (area made by two straight lines in circle) of 72 ° for the first category "Comedy" by the help of a protactor. Simlarly make a sector of 90°, 108°, 18° and 72° for Action, Romance, Drama and Sci- Fi respectively
Specify different colors for different categories in the pie chart.
You will obtain a pie chart like given below:
Pie charts are a way of displaying data. They get their name because they look a bit like pies from above, with different sized slices of pie being cut depending on the data you have.
I your exam, you'll need to know both how to read pie charts, and also how to construct your own.
First things first, we need to know how to read the data represented in a pie chart.
The chart below represents the results of a survey on a class of 24 students to find out their favourite colours.
Looking at the graph we can tell straight away, that half the class picked blue as their favourite colour. Yellow came in second with a quarter of the class choosing it, then red and green joint last with an eigth each.
So by using the fractions of the circle, we can see that 12 students favour blue, 6 favour yellow, 3 favour green and 3 favour red.
To fully understand what a pie chart is you will need to know how to construct one
Constructing a Pie chart:
In order to construct a pie chart, we first need to find out the fraction of the total that each slice represents.
- First work out the total frequency. This can be done by adding all the frequencies together.
- Find the fraction of the total frequency for each colour. = Frequency/Total Frequency
- Then find the angle. = (Frequency/Total frequency) x 360
This will give you the angles shown in the table below, and then you just have to draw the graph using those angles.
|Blue||5||(5÷40)x360 = 45|
|Red||10||(10÷40) x 360 = 90|
|Green||10||(10÷40) x 360 = 90|
|Purple||15||(15÷40) x 360 = 135|
To draw a pie chart, follow the steps listed below:
- Draw a circle using a compass
- From the centre draw a line vertically up. This will be the 0° line.
- Using a protractor and the 0° line use the angles you worked out to plot the pie char
Follow the links below to see how this topic has appeared in past exam papers