The class marks of a distribution are 6,10,14,18,22,26,30. Find the class size and class interval.

We observe that 10 - 6 = 4, 14 - 10 = 4 …& so one.

Hence, class size is 4.

Now, the difference between the values of two consecutive class marks is 4, therefore we subtract 4/2 = 2 from each class mark to get the lower limit of the corresponding class interval and add 5 to each class mark to get the upper limit.

Thus, the class intervals are

4 - 8

8 - 12

12 - 16

16 - 20

20 - 24

24 - 28

28 - 32