If 10, 15, 20, … are respectively the mid-value of the classes of a grouped frequency distribution, then the class whole mid-value is 25 is :

1. 20 - 27

2. 22.5 - 27.5

3. 21.5 - 28.5

4. 21 - 28

The width of each class interval of a grouped frequency distribution is 8. The lower boundary of the class whose mid-value is 10 is :

1. 2

2. 4.5

3. 5.5

4. 6

Class marks of a distribution are: 47, 52, 57, 62, 67, 72, 77, 82. Class size of the given distribution is :

1. 5

2. 6

3. 7

4. 2

Mid value for the class interval 19.5 - 29.5 is :

1. 14.5

2. 24.5

3. 15.5

4. 25.5