Question

The following are class mark, of a frequency distribution 12, 16, 20, 24, 28. Give the class.

Answer 1

Class size = 16 − 12 = 4

Now, since the class marks are the midpoints, we can derive the class intervals by subtracting and adding half of the class width (which is `4/2`= 2) to each class mark:

For the class mark 12:

Lower limit = 12 − 2 = 10

Upper limit = 12 + 2 = 14

Class = 10 - 14

For the class mark 16:

Lower limit = 16 − 2 = 14

Upper limit = 16 + 2 = 18

Class = 14 - 18

For the class mark 20:

Lower limit = 20 − 2 = 18

Upper limit = 20 + 2 = 22

Class = 18 - 22

For the class mark 24:

Lower limit = 24 − 2 = 22

Upper limit = 24 + 2 = 26

Class = 22 - 26

For the class mark 28:

Lower limit = 28 − 2 = 26

Upper limit = 28 + 2 = 30

Class = 26 - 30

The  class intervals are: 10 - 14, 14 - 18, 18 - 22, 22 - 26, 26 - 30