** BAR CHART (OR GRAPHS) AND THEIR USES IN ECONOMICS**, What is a bar chart? Bar chart or graph is a graph made up of bars of rectangles which are of equal width and whose lengths are proportional to the quantities they represent.

## features of a bar chart

The major characteristic of the bar chart is that the body of the bars must not touch each other. There must be a space or gap between one bar and another. Bar may be arranged vertically or horizontally.

__Types of bar chart__ or bar graph

__Types of bar chart__

There are three major types of bar charts. These are:

- Simple bar chart
- Component b. charts and
- Multiple ba chart

**Simple bar chart**

Simple b chart is used when the data given are made up of only one item or component

.

The b chart can be presented by tabulated data with evenly spaced bars, separated by gaps with the length proportional to the magnitude of the value given.

**Exemplary use of a simple bar chart** or bar graph

The table represents the quantity of cocoa production in Nigeria between 1960 and 1967. Represent the information or data by a chart.

Table (a): Cocoa production in Nigeria between 1960 and 1967.

Year | Cocoa production (Tons) |

1960 1961 1962 1963 1964 1965 1966 1967 | 7,000 1,500 3,000 6,000 8,500 5,000 4,000 3,500 |

Solution

Table (a): Cocoa production in Nigeria between 1960 and 1967.

Year | Cocoa production (Tons) |

1960 1961 1962 1963 1964 1965 1966 1967 | 7.0 1.5 3.0 6.0 8.5 5.0 4.0 3.5 |

- From the figures given, using the scale: 1cm: 1000 tonnes, the figures can be reduced to simple ones when they are divided by 1000.
- The new values will now be.

__Useful information to be derived from using a bar graph__

__Useful information to be derived from using a bar graph__

- The year with the highest cocoa production can be calculated. The year is 1964
- The year with the least cocoa production can also be calculated. The year is 1961.
- The total cocoa production from 1960 to 1967 can be calculated, i.e. 7,000 + 1,500 + ……… + 4, 000 + 3, 000 = 38,500
- The average or mean production can also be calculated by adding the total production (as in (iii) above) and dividing it by the number of years (8 years), i.e.

7,000 + 1, 5000 + ……. = 4,000 + 3,500

8

=38,500

8 = 4, 812.5 tons/year

##### (b) __what are Component bar chart__

__what are Component bar chart__

A component bar is used when the data involved are of two variables.

**Example**

Represent the population of males and females (in millions) table in towns in Edo State in 1999

Towns | Male (m) | Female (m) | Total (m) |

Uromi | 80 | 60 | 140 |

Ubiaja | 60 | 50 | 110 |

Ekpoma | 70 | 30 | 100 |

Irrua | 30 | 15 | 45 |

Solution

WEED AND THEIR BOTANICAL NAMES

Using a graph sheet, choose a suitable scale for the graph, e.g. 1cm represent 10 units, the graph (component chart above is then drawn. __COMPONENT BAR CHARTS SHOWING THE ____POPULATION ____OF SOME TOWNS__

__MULTIPLE BAR CHART AND USAGE__

__MULTIPLE BAR CHART AND USAGE__

b. Multiple bar charts: The multiple chart is used when there are about three or more variables in a given data. It has multiple bars, each of which stands for a component variable.

Example

Represent Nigeria’s export of cocoa (table 2.7) from Ibadan, Abeokuta and Akure in 1969, 1970 and 1980 by a bar chart.

Table 2.7: Nigeria’s export of cocoa from Ibadan, Abeokuta and Akure in 1960, 1970 and 1980.

Towns | 1960(tons) | 1970(tons) | 1980(tons) |

Ibadan | 30 | 40 | 50 |

Abeokuta | 40 | 30 | 60 |

Akure | 50 | 70 | 40 |

Solution using bar chart

Using a graph sheet, choose a suitable scale for the graph, e.g. 1cm to represent 1o units, the graph (a multiple chart is then drawn.

Importance of production and factors of production

Production is important because of the following:

Availability of goods and services: Production helps to ensure that goods and services are made available for use by human beings.

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