I’m prepping for a test and I’m stuck on histograms with uneven class widths: my brain keeps shouting “tallest bar wins,” but then I read it’s the area that matters, so I tried computing frequency densities (like 18/6 = 3 and 12/4 = 3) and now I can’t tell if I’m supposed to compare heights, widths, or the rectangle areas when they ask which interval has the most values or where the peak is-what do I actually look at? Any help appreciated!
Welcome to Maths For Fun – where mathematical curiosity meets pure enjoyment for learners of all ages! Founded by a team of lifelong maths enthusiasts, we believe that numbers aren’t just for tests – they’re for exploration, discovery, and delight. Whether you’re eight or eighty, a beginner or a seasoned problem solver, you’ll find a growing collection of logic based games and puzzles that cover every corner of mathematics.
















2 Responses
Think of an unequal-width histogram like a garden of flowerbeds: the width is how wide the bed is, the height is how densely it’s planted, and the area is how many flowers are actually in there. The rule that keeps everything sane is frequency density = frequency ÷ class width, and the bar’s area (height × width) represents the number of values in that interval. So: if they ask “which interval has the most values,” you look at area (equivalently, the frequency), not just the height-your 18/6 = 3 and 12/4 = 3 have equal heights (same density), but the first has more values because its area is bigger (18 vs 12). If they ask “where is the peak” or “modal class” in a histogram with unequal widths, that usually means the class with the highest frequency density-i.e., the tallest bar-because “mode” is about where the data are most concentrated per unit on the x-axis. A skinny, very tall bar can be the peak (highest density) even if it doesn’t contain the most values overall. Tiny caveat: this all assumes the vertical axis is frequency density (as it should be for unequal widths); if your plot literally labels the y-axis “frequency” with changing widths, that’s nonstandard and comparisons get messy. But in almost all test settings: most values → compare areas; peak/modal class → compare heights (densities).
You’ve got it: with unequal widths, the area of a bar tells you how many values are in that interval, but the “peak” is where the height (frequency density) is greatest. Think of each bar like a garden bed-its footprint (area) tells how many plants, while the tallest foliage (height) shows where they’re packed most tightly.