Pie chart

It is a circular graph which is used to represent data

Constructing Circle Graphs or Pie Charts
A pie chart (also called a Pie Graph or Circle Graph) makes use of sectors in a circle. The angle of a sector is proportional to the value of the data.

The formula to determine the angle of a sector in a circle graph is:

Steps

1. Calculate the angle of each sector, using the formula

2. Draw a circle using a pair of compasses
3. Use a protractor to draw the angle for each sector.
4. Label the circle graph and all its sectors.

Example 1:

In a class, has 45 boys and 75 girls. Draw a Pie chart to represent the numbers of students in the class.

Solution:

Total number of students = 45 + 75 = 120

Size of the angle of boys =

Size of the angle of girls =

Note that after calculating the angle of each component the total angle = 3600

That is the angle representing boys  + angle representing girls or 135 + 225 = 360

Draw the circle of any radius, measure in each sector. Label each sector of the pie chart.

Example 2

The Pie-chart below shows the population in three villages: Kibira, Mwiga and Ibembe

(a)      Given that the population of Ibembe is 1080. Find the population of.

(i)   Kibira

First find the value of  x

3x + (x + 30) + (3x – 20) = 360⁰ (total angle of circles)

7x + 10 = 360

7x = 350

X = 50

Angle Ibembe  =  50 + 30 = 80⁰

Let the total population be Y

For revision questions download PDF

Pie chart- upper primary

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