Pie Chart Or Circle Graph


Pie Chart – You unconsciously see and use data in your day to day life. It is defined as a collection of information gathered by observation, measurement, research or analysis and may consist of facts, numbers, names, figures or even description of things. Data is classified into qualitative or quantitative depending upon the nature of the information it provides. Moreover, data can be organised in the form of graphs, charts or tables. One such representation of data is a pie chart. In this article, we will learn more about a pie chart and its construction.

What is a Pie Chart?

A pie chart is a circular chart in which data is displayed in the form of pie slices.

Pie Chart

  • The size of an arc of each slice is proportional to the quantity it represents.
  • The bigger the slice, the bigger portion of the whole is represented by it.
  • The total angle formed at the center is 360 degrees, which is the sum of the fractions of all the sectors.

Construction of a Pie Chart

A pie chart basically shows the relationship between the whole and its parts. Thus, for its construction, we need to find how they are related as a fraction, and then convert it into a scale of 360 degrees to obtain the angle that the part subtends at the center. It is given by:

Pie Chart

Let us understand the construction with the help of an example. Say, John makes a purchase of Rs 720 in a grocery store. He buys ketchup for Rs 120, Maggi for Rs 60, sugar for Rs 30, eggs for Rs 40, candies for Rs 110, Silk Bubbly for Rs 60 and rice Rs 300. We are required to draw a pie chart for the purchase.

  • Find the central angle for each of the component using the formula discussed above.

Pie Chart

  • Draw a circle of any convenient radius and mark its center.
  • Draw any radius.
  • Take up the first component (here, 60° for ketchup). Place a protractor on the radius and draw a new radius which makes 60° with it.
  • From the new radius, draw the next component’s central angle.
  • Repeat the same for all the components.

Pie Chart

We obtained the required pie chart.

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Practise This Question

The content of the carbon dioxide in the air is 500 ppm(parts per million). What is the content of Oxygen in the air ?