Histograms with Unequal Intervals

When bar widths differ, frequency density does the work — here's how to read and draw these charts.

Frequency Density

Why histograms use frequency density on the y-axis when class widths differ — the formula, the logic, and worked examples from Nova.
Reading Histograms

Extract frequencies, estimate totals and find proportions from a histogram — step-by-step with worked examples for unequal class widths.