Question

The class marks of a frequency distribution are: 15, 25, 35, 45, 55, 65 and 75. Determine the class limits.

Answer 1

The class marks are uniformly spread.
The class size is the difference between anty two consecutive class marks.
Class size
= 25 - 15
= 10
The lower limit of the first class 

= `15 - (10)/(2)`

= 15 - 5
= 10
The upper limit of the first class

= `15 + (10)/(2)`

= 15 + 5
= 20
Thus, the first class interval is 10 - 20
Similarly, we can find the class limits of all the class marks given.

Class Marks	Class limits
15	10 - 20
25	20 - 30
35	30 - 40
45	40 - 50
55	50 - 60
65	60 - 70
75	70 - 80