Frequency Density in Histogram

When class intervals are unequal in a histogram, which value is used instead of absolute frequency?

Correct Answer Explanation

When class intervals are unequal, frequency density (class frequency divided by width of the class interval) is used instead of absolute frequency.

Key Points:

• Frequency density = Class frequency ÷ Width of class interval.
• When intervals are equal, area can conveniently be represented by frequency itself.
• When bases vary, heights must be adjusted to yield comparable measurements.
• This ensures that areas of rectangles remain proportional to frequencies.

Why Other Options Are Wrong

• A. Cumulative frequency: This is used in ogives, not histograms with unequal intervals.
• C. Relative frequency: While related, the specific term used is frequency density.
• D. Modal frequency: This refers to the highest frequency, not an adjustment method.