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Exa: Marks of 30 students are as follows-It is in the form of Raw data.

92, 92,95, 36,36, 40, 60,60,70, 50, 50,56,56,60, 70, 40,40,40,50,60, 70,70,72,80,88,
88,92, 10,20,36

These 30 students marks are expressed in the form of ungrouped frequency
distribution table.

Marks obtained 10 20 36 40 50 56 60 70 72 80 88 92 95
(x i)
Number of 1 1 3 4 3 2 4 4 1 1 2 3 1
student ( f i)

*Grouped Data: It is the data that has been organised into several groups, called
classes.

These 30 students marks are represented in a grouped frequency distribution table.

Class interval 10 - 25 25 - 40 40 - 55 55 - 70 70 - 85 85 - 100

Number of students 2 3 7 6 6 6

Types of classes:(Exclusive and Inclusive)

*Exclusive form of data-In this form only lower limit is included but upper limit is
excluded in each class,i.e. 10-25 means the observation which is equal to 10 and
between and 10 and 25 will be counted.(25 is excluded)

Exa:

Class interval 10 - 25 25 - 40 40 - 55 55 - 70 70 - 85 85 - 100

Number of students 2 3 7 6 6 6

*Inclusive form of data: In this form both lower limit and upper limit is included in each
class,i.e. 10-14 means the observation which are equal to 10 as well as 14 and their
between will be counted.

Marks 10 - 14 15 - 19 20 - 24 25 - 29 30 - 34

Number of 4 6 12 5 3

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