FORMATION OF FREQUENCY TABLE FOR UNGROUPED DATA

Here we are going to see how to create a frequency table for ungrouped data.

Advantages of creating a frequency table :

By creating a frequency table, we may easily find out which data is more obvious.

To create frequency table, we use three columns.

In the 1^st column, we have to write the given numbers.

In the 2^nd column, we have to write "tally marks"

In the 3^rd column, we have to write frequency.

Definition of tally marks :

‘|’ is called a ‘tally mark’. It is difficult to count if there are more number of tally marks. Therefore to make it easier to count, we change it as follows.

The examples given below will illustrate the above concept.

Example 1 :

Consider the following data:

15, 17, 17, 20, 15, 18, 16, 25, 16, 15, 16, 18, 20, 28, 30, 27, 18, 18, 20, 25, 16, 16, 20, 28, 15, 18, 20, 20, 20, 25.

Form a frequency table.

Solution :

Example 2 :

The marks obtained by 50 students in a Mathematics test with maximum marks of 100 are given as follows:

43, 88, 25, 93, 68, 81, 29, 41, 45, 87, 34, 50, 61, 75, 51, 96, 20, 13, 18, 35, 25, 77, 62, 98, 47, 36, 15, 40, 49, 25, 39, 60, 37, 50, 19, 86, 42, 29, 32, 61, 45, 68, 41, 87, 61, 44, 67, 30, 54, 28.

Prepare a frequency table for the above data using class interval.

Solution :

Total number of values  =  50

Range = Highest value  -  Lowest value

  =  98 – 8  =  90

Let us divide the given data into 10 classes.

Length of the Class interval = Range / Number of class interval

  =  90/10

  =  9

The frequency table of the marks obtained by 50 students in a mathematics test is as follows:

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