Question

Prepare a frequency distribution from the following data:

Mid-Points	25	35	45	55	65	75
Frequency	6	10	9	12	8	5

Answer 1

The class interval can be calculated from the mid-points using the following adjustment formula.

The value obtained is then added to the mid point to obtain the upper limit and subtracted from the mid-point to obtain the lower limit.

For the given data, the class interval is calculated by the following value of adjustment.
$\mathrm{Value}\mathrm{of}\mathrm{adjustment}=\frac{35-25}{2}=5$

Thus, we add and subtract 5 to each mid-point to obtain the class interval.

For instance:

The lower limit of first class = 25 – 5 = 20

Upper limit of first class = 25 + 5 = 30

Thus, the first class interval is (20 − 30). Similarly, we can calculate the remaining class intervals.


Frequency Distribution

Mid Value	Class Interval	Frequency
25 35 45 55 65 75	20 − 30 30 − 40 40 − 50 50 − 60 60 − 70 70 − 80	6 10 9 12 8 5
		${\sum }_{}^{}f=50$