The word ‘data’ means collection of
information in the form of numerical figures, or a
set of given facts.
Visual representation of data will help us to
understand it better and remember the facts
When some information is collected and presented randomly, then it is called raw data.
- The marks obtained by 10 students of a class in a test are:
76, 83, 95, 100, 56, 32, 80, 67, 75, 46
A data classified into groups is called grouped data.
- The following table gives the data regarding the favourite game of 100 students of
of handling data in a systematic order
Data in raw form can be represented in the form of pictures and diagrams.
It makes the given data attractive to the observer.
Also, it is easy to understand and to compare it with other information.
Representation of Numerical Data :
Pictographs represent data through appropriate pictures.
In pictographs, the same type of symbol or picture is used to represent the data. Each
symbol is used to represent a certain value.
For example, one symbol may represent 25 students.
The following pictograph represents the number of students coming to a college by
different means of transport:
Distribution of cars in the month of July, August and September :
A representation of data with the help
of bars or rectangles in a diagram is called
a bar graph or a bar diagram.
Each bar = one value of data, and hence,
there are as many bars as the number of
values in the data
Length/height of bar = value of item,
Frequency Distribution Table
Grouping the raw data :
Each group is called a class interval
Lower Class Limit
Upper Class Limit
Upper Class Limit – Lower Class Limit = Width/size of class
Frequency : no. of times a particular item appears with
particular class interval
Fill up the rows with tally marks and will count the total
number of tally marks in each group.
Number of tally marks in each group is listed in the
Double Bar Graph
A graph showing two sets of data simultaneously is called a double bar graph.
It is useful for comparing two sets of data.
Example : The following graph shows the strength of boys and girls in a school in different