PIE CHARTS (OR GRAPHS) AND ITS USES IN ECONOMIC what is a pie chart:
A pie chart or graph is a simple circle of any convenient size which is divided into sections or sectors, each of which is proportional to the quantity or value it represents.
HOW IS A PIE CHART MEASURED?
The pie chart is usually measured either in percentage or in degrees with the aid of a mathematical device called a protractor.
The entire circle is represented by 360o or 100% and each sector is measured in degrees with the aid of a protractor.
Methods of Constructing a pie chart
Add up the total figure of the product or value under consideration.
Work out the percentage or degree of the total which each component part represents.
Draw a circle of a convenient size.
Divide the circle up into sectors suspended by these angles calculated in step (ii) above using a protractor.
Write the percentage or degree of each sector by it.
Use a key where the information cannot be written inside the circle to show what each sector represents.
HOW TO USE A PIE CHART TO SOLVE ECONOMIC DATA REPRESENTATION
Example 1 of the proper use of the pie chart
Represent the information I table by means of a piechart, the value of the most important exports of Nigeria in 1980, both in percentages and in degrees.
Value of the most important exports in Nigeria in 1980.
|Export product||Value in millions|
- Add up the total value of all the products, i.e. 200 + 140 + 240 + 50 + 90 = 720.
- Arrange your workings or calculations as follows:
|Export Product||Value in Millions (||Workings in percentage (%)||Workings in degree (0o) Angle of sector|
Using the values in degree, i.e. 100%, 70o, 120o, 25o and 45o, a pie chart in Fig. 2.2 is now drawn using a protractor.
Pie chart showing value of the most important exports of Nigeria in 1980.
The table below shows the sectoral allocation of a country’s budget. Illustrate the data accurately with a pi chart. Show your workings clearly.
Table 2.4: Sectoral allocation of a country’s budget.
Sector Amount (
|Sector||Amount (N Million) (Angle of Sector)||Workings in degrees|
Total 100 360o
- Add up the total value of all the sectors, i.e. 30 + 25 + 15 + 10 + 20 = 100
- Arrange your workings or calculations in the following manner only in degrees.
- Using the values in degrees, i.e. 108o, 90o, 54o, 36o and 72o, a pie chart is now drawn.