The height of a histogram does not represent the frequency of the corresponding class interval.
The height of a histogram represents the frequency of the data of a class interval and width of the histogram represents class width.
The height of the bars in a histogram represents the frequency of the data (in the considered class interval) and width of the histogram represents class width.
How does the procedure of drawing a histogram differ when class intervals are unequal in comparison to equal class intervals in a frequency table?