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
ff
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 360^{o }or 100% and each sector is measured in degrees with the aid of a protractor.
h

 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 (0^{o}) Angle of sector 
Cocoa  20  200  
Groundnut  140  
Petroleum  240  
Coal  50  
Others  90  
TOTAL  720 
Using the values in degree, i.e. 100%, 70^{o,} 120^{o}, 25^{o} and 45^{o}, 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 100 360^{o}
 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. 108^{o}, 90^{o}, 54^{o}, 36^{o} and 72^{o}, a pie chart is now drawn.