# Histograms with unequal bar width

I can construct a histogram from a table.

# Histograms with unequal bar width

I can construct a histogram from a table.

## Lesson details

### Key learning points

- Sometimes data is presented using unequal class widths
- In order to compare, frequency density is used
- Frequency density is proportional to the frequency per unit for the data in each class
- Frequency is proportional to the area of the bar

### Common misconception

Histograms with unequal bar widths are plotted against the frequency and/or pupils read the frequency density as the frequency of the class width.

Show what a histogram with unequal bar widths looks like when plotted against frequency. This visual aid will show pupils the distribution of data is difficult to see.

### Keywords

Frequency density - Frequency density is proportional to the frequency per unit for the data in each class. Often, the multiplier is 1 meaning that frequency density = frequency ÷ class width.

### Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

## Video

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## Starter quiz

### 6 Questions

## Exit quiz

### 6 Questions

Frequency density -

is proportional to the frequency per unit for the data in each class.

Population density -

is the number of people living per unit of area.

Substance density -

is measured as the substance's mass per unit of volume.

$$0 < w \leq 5$$ -

Frequency density = 4

$$5 < w \leq 15$$ -

Frequency density = 2

$$15 < w \leq 30$$ -

Frequency density = $$\frac{4}{3}$$

$$0 < l \leq 15$$ -

Frequency density = 1.6

$$15 < l \leq 20$$ -

Frequency density = 4

$$20 < l \leq 30$$ -

Frequency density = 1.4

$$30 < l \leq 35$$ -

Frequency density = 3.2