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.
other economic tools and table
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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.
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- public enterprises
- private enterprises
- limited liability companies
- migration
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 |
Cocoa | 200 |
Groundnut | 140 |
Petroleum | 240 |
Coal | 50 |
Others | 90 |
Solution
- 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 |
Cocoa | 20 | 200 | |
Groundnut | 140 | ||
Petroleum | 240 | ||
Coal | 50 | ||
Others | 90 | ||
TOTAL | 720 |
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.
Example 2
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 (N Million)
Health 30
Education 25
Housing 15
Manufacturing 10ul
Agriculture 20
Solution
Sector | Amount (N Million) (Angle of Sector) | Workings in degrees |
Health | 30 | |
Education | 25 | |
Housing | 15 | |
Manufacturing | 10 | |
Agriculture | 20 | |
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.