How does the procedure of drawing a histogram differ when class intervals are unequal in comparison to equal class intervals in a frequency table?

Procedure of drawing a histogram differ when class-intervals are unequal in comparison to equal class-intervals in a frequency table. In the case of equal class-intervals, no adjustment is made. In this case, the width of the rectangles would be of equal width, whereas the length of the rectangles would be different in proportion to the frequencies of the class-intervals.

In case of unequal class-intervals, frequencies of unequal class-intervals are adjusted. For adjustment, following steps are taken into account:

1. We first locate the lowest class-interval. We make no adjustment in this class-interval.

2. We adjust the frequencies of all other classes with the lowest class-size using the following formula:

Adjusted frequency

3. The histogram is made on the basis of adjusted frequencies and not the frequencies given originally.

4. We below given the adjusted frequency for the further clarification. Class-Interval f Adjusted frequency

It may be pointed out that the width of the rectangles would be different