Data Handling, NCERT NOTES, Class 6

Data Handling

Data
Data is a collection of numbers gathered to give some information.

Frequency

• Frequency is the number of times a particular value occurs in a given data .
• Eg : Marks scored by different students in a class: 1,2,2,4,3,3.

                  $\begin{array}{cc}Marks& Frequency\\ 1& 1\\ 2& 2\\ 3& 2\\ 4& 1\end{array}$

Organised Data

• Data should be organised properly.
• This helps in extracting information.
• Example: In a class, 20 students were asked to choose one fruit from Banana, Orange, Apple and Guava.
                  The following shows organised data for the above information is given below.
                  $\begin{array}{cc}Fruit& Numberofstudents\\ Banana& 8\\ Orange& 3\\ Apple& 5\\ Guava& 4\\ & \end{array}$

Prioritizing Data

• Data can be prioritized or it can be organised in a particular order according to importance.
• Example: Following are the names of students in a class: Anu, Shameer, Kiran, John. Prioritize the data according to alphabetic order. On prioritising the data, the new order of names become Anu, John, Kiran and Shammer. 

How to organise data?

• Data can be organised in different ways. It can be organised in
  (i) Alphabetical order 
  (ii) In ascending and descending order.
• Example: Arrange the following data according to the birth year.

          $\begin{array}{cccc}Ravi& Shekhar& Sunny& Asha\\ 1970& 1988& 1979& 1920\end{array}$

          Organised Data : $\begin{array}{cccc}Asha& Ravi& Sunny& Shekhar\\ 1920& 1970& 1979& 1988\end{array}$

Scaling Factor

• The large numbers cannot be represented in a bar graph, so the scaling factor is used to reduce or scale down large numbers. 

Pictographs

• Pictograph is a pictorial representation of data.
• Here data is represented using images of the objects.

Interpretation of pictographs

The number of strawberries eaten by various people is shown below.


Question. Find the number of apples eaten by Margaret, Susan, Maria
                and Dorothy.
Solution: Here each symbol of strawberry represents two strawberries.
               $\Rightarrow$ Margaret ate 8 strawberries, Susan ate 4 strawberries,
               Maria ate 2 strawberries and Dorothy ate 12 strawberries.
               So, the total number of strawberries eaten by all the four is
               30.                                   

Bar graphs

• The graphical representation of data using bars of uniform width drawn vertically or horizontally with different lengths is called as bar graphs/bar diagrams.
• Bar diagrams consist of two axes: X axis and Y axis.
• The following is a bar graph showing birthday of students in a class.

Interpretation of bar diagrams

• Given below are the marks scored by students in mathematics. Calculate the sum of marks scored by A and C.

     Solution: 
                    $\begin{array}{cc}Student& MarksObtained\\ A& 8\\ B& 14\\ C& 9\\ D& 5\end{array}$
                   Sum of marks scored by A and C = 8 + 9 = 17
                   $\therefore$ The required sum is 17.