# Pie Chart

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

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 means 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
$1500$
${360^ \circ }$