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Mean, median and mode

When the distribution of data is symmetrical, the value of the mean and the median are similar, as shown in the graph of Australian Prime Ministers' heights.

 

24 values plotted from 166 to 194 centimetres, roughly equally spread about 178. The mean is shown as equal to the median.

Dot plot of Australian Prime Ministers' heights.

 

Red symbol like an upside down T
The red upside-down letter T on the horizontal axis indicates the median.
blue triangle outline
The blue triangle indicates the mean. If the symbols for median and mean overlap, it would indicate that the mean is equal to the median.
green asterisk
The green asterisk represents the mode in the dot plot of Mark Taylor's first innings scores. This skewed distribution shows the three measures of centre for that data set are distinctly different.

 

Dot plot of 63 cricket scores from 0 to 219, with many bunched near 0 and only 4 greater than 120. Positively skewed distribution with mode less than median and the median less than the mean.

Mark Taylor's first innings scores.

Contrasting the median and mean

This activity is designed to help students distinguish between means and medians in symmetric and skewed data sets.

Curriculum links

Year 7: Calculate mean, median, mode and range for sets of data. Interpret these statistics in the context of data

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