CONSTRUCTION OF PIE CHART

Here, we take a circle and the whole circle is divided into sectors. The size of each sector is proportional to the activity or information it represents.

Because the sectors resemble the slices of a pie, it is called a pie chart. 

Important Note

In a pie chart, the various observations or components are represented by the sectors of a circle and the whole circle represents the sum of the value of all the components .Clearly, the total angle of 360° at the center of the circle is divided according to the values of the components .

The central angle of a component is

=  [Value of the component / Total value] ⋅ 360°

Sometimes, the value of the components are expressed in percentages. In such cases,

The central angle of a component is

=  [Percentage value of the component / 100] ⋅ 360°

Steps to Construct a Pie-Chart

Step 1 :

Calculate the central angle for each component , using the above formula.

Step 2 :

Draw a circle of convenient radius.

Step 3 :

Within this circle, draw a horizontal radius.

Step 4 :

Draw radius making central angle of first component with horizontal radius; this sector represents the first component. From this radius, draw next radius with central angle of second component; this sector represents second component and so on, until we exhaust all components.

Step 5 : 

Shade each sector differently and mark the component it represents.

Step 6 : 

Give the heading for each component.

Examples

Example 1 : 

The number of hours spent by a school student on various activities on a working day, is given below. Construct a pie chart using the angle measurement.

Draw a pie chart to represent the above information.

Solution :

The central angle of a component is

=  [Value of the component / 100] ⋅ 360°

We may calculate the central angles for various components as follows :

From the above table, clearly, we obtain the required pie chart as shown below.

Example 2 :

The following table shows the half yearly budget of a family

Draw a pie chart to represent the above information.

Solution :

The central angle of a component is

=  [Value of the component / 100] ⋅ 360°

We may calculate the central angles for various components as follows :

From the above table, clearly, we obtain the required pie chart as shown below.

Example 3 : 

The result of an examination of a school is as follows :

Draw a pie chart to represent the above information.

Solution :

The central angle of a component is

=  [Value of the component / 100] ⋅ 360°

We may calculate the central angles for various components as follows :

From the above table, clearly, we obtain the required pie chart as shown below.

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