Pie Chart

Pie chart can used to compare the relation between the whole and its components. Pie chart is a circular diagram and the area of the sector of a circle is used in pie chart. Circles are drawn with radii proportional to the square root of the quantities because the area of a circle is 2\pi {r^2}.

To construct a pie chart (sector diagram), we draw a circle with radius (square root of the total). The total angle of the circle is {360^ \circ }. The  angles of each component are calculated by the formula.

 Angle\,of\,Sector = \frac{{{\text{Component  Part}}}}{{{\text{Total}}}} \times {360^ \circ }

These angles are made in the circle by mean of a protractor to show different components. The arrangement of the sectors is usually anti-clock wise.

Example:

The following table gives the details of monthly budget of a family. Represent these figures by a suitable diagram.

Item of Expenditure

Family Budget
Food
\$ {\text{ 600}}
Clothing
\$ {\text{ 100}}
House Rent
\$ {\text{ 400}}
Fuel and Lighting
\$ {\text{ 100}}
Miscellaneous
\$ {\text{ 300}}
Total
\$ {\text{ 1500}}

Solution:

The necessary computations are given below:

 Angle\,of\,Sector = \frac{{{\text{Component  Part}}}}{{{\text{Total}}}} \times {360^ \circ }

Items

Family Budget
Expenditure $
Angle of Sectors
Cumulative Angle
Food
600
{144^ \circ }
{144^ \circ }
Clothing
100
{24^ \circ }
{168^ \circ }
House Rent
400
{96^ \circ }
{264^ \circ }
Fuel and Lighting
100
{24^ \circ }
{288^ \circ }
Miscellaneous
300
{72^ \circ }
{360^ \circ }
Total
1500
{360^ \circ }
 

Pie Chart

Pie Chart