How classes can be formed while presenting the data?
Classes can be formed in two ways :
(i) Exclusive type, (ii) Inclusive type.
(i) Exclusive Type : When the class intervals are so fixed that the upper limit of one class is the lower limit of the new class, it is known as exclusive method of clasfication.
For example:
|
Marks (percentage) |
No. of students |
|
0 – 10 |
15 |
|
10 – 20 |
17 |
|
20 – 30 |
22 |
|
30 – 40 |
30 |
|
40 – 50 |
39 |
|
50 – 60 |
45 |
In this method, higher value of the variable in the class is not included in that class. i.e.
|
Marks (percentage) |
No. of Students |
|
0 and more but less than 10 |
15 |
|
10 and more but less than 20 |
17 |
|
20 and more but less than 30 |
22 |
|
30 and more but less than 40 |
30 |
|
40 and more but less than 50 |
39 |
|
50 and more but less than 60 |
45 |
(ii) Inclusive Type : In this method, the students getting say 39% marks will be included in the class 30 - 39 itself i.e.
|
Marks (Percentage) |
No. of Students |
|
0 – 9 |
5 |
|
10 – 19 |
8 |
|
20 – 29 |
7 |
|
30 – 39 |
13 |
|
40 – 49 |
25 |
