Bar Graphs

Construction of Bar Graphs

Now we will discuss about the construction of bar graphs or column graph. In brief let us recall about, what is bar graph?

Bar graph is the simplest way to represent a data.

● In consists of rectangular bars of equal width.

● The space between the two consecutive bars must be the same.

● Bars can be marked both vertically and horizontally but normally we use vertical bars.

● The height of bar represents the frequency of the corresponding observation.

For example, let us observe the following data of the bar graph.

The following data gives the information of the number of children involved in different activities.

Activities	Dance	Music	Art	Cricket	Football
No. of Children	30	40	25	20	53

How to Construct a Bar Graph?

Steps in construction of bar graphs/column graph:

● On a graph, draw two lines perpendicular to each other, intersecting at 0.

● The horizontal line is x-axis and vertical line is y-axis.

● Along the horizontal axis, choose the uniform width of bars and uniform gap between the bars and write the names of the data items whose values are to be marked.

● Along the vertical axis, choose a suitable scale in order to determine the heights of the bars for the given values. (Frequency is taken along y-axis).

● Calculate the heights of the bars according to the scale chosen and draw the bars.

Bar graph gives the information of the number of children involved in different activities.

Solved examples on construction of bar graphs:

1. The percentage of total income spent under various heads by a family is given below.

Different Heads	Food	Clothing	Health	Education	House Rent	Miscellaneous
% Age of Total Number	40%	10%	10%	15%	20%	5%

Represent the above data in the form of bar graph.

2. 150 students of class VI have popular school subjects as given below:

Subject	French	English	Maths	Geography	Science
Number of Students	30	20	26	38	34

Draw the column graph/bar graph representing the above data.

Solution:

Take the subjects along x-axis, and the number of students along y-axis

Bar graph gives the information of favourite subjects of 150 students.

3. The vehicular traffic at a busy road crossing in a particular place was recorded on a particular day from 6am to 2 pm and the data was rounded off to the nearest tens.

Time in Hours	6 - 7	7 - 8	8 - 9	9 - 10	10 - 11	11 - 12	12 - 1	1 - 2
Number of Vehicles	100	450	1250	1050	750	600	550	200

Bar graph gives the information of number of vehicles passing through the crossing during different intervals of time.