A histogram represents continuous grouped data with adjacent bars. When class widths differ, height alone cannot represent frequency fairly. Use frequency density=frequency/class width, so bar area equals frequency. **Time (minutes)** | **Frequency** | **Width** | **Density** 0–10 | 8 | 10 | 0.8 10–20 | 16 | 10 | 1.6 20–40 | 20 | 20 | 1 40–60 | 6 | 20 | 0.3 The 20–40 bar is lower than the 10–20 bar but has more observations: its area is 20(1)=20, compared with 10(1.6)=16. The tallest bar identifies the greatest density, not necessarily the greatest frequency. Label the vertical axis frequency density. To estimate a count within part of a class, use the corresponding fraction of its bar area, assuming the observations are evenly distributed within that class.

A histogram represents continuous grouped data with adjacent bars. When class widths differ, height alone cannot represent frequency fairly. Use \(\text{frequency density}=\text{frequency}/\text{class width}\), so bar area equals frequency.

The 20–40 bar is lower than the 10–20 bar but has more observations: its area is \(20(1)=20\), compared with \(10(1.6)=16\). The tallest bar identifies the greatest density, not necessarily the greatest frequency.

Label the vertical axis frequency density. To estimate a count within part of a class, use the corresponding fraction of its bar area, assuming the observations are evenly distributed within that class.

Statistics

Cambridge IGCSE Mathematics 0580. Initial catalogue covers the assessed demands of February/March 2026 Paper 22; further Core and Extended mappings require paper-level scope review.

Histogram area represents frequency

Histogram area represents frequency