Measures of central tendency
Mean
Add all the measurements together then divide by the number of measurements taken.
Median
Arrange the data in order and take the middle value as the median.
Mode
The value which occurs most often.
Measures of dispersion
Dispersion
The spread of data around the average.
Range
Range is the distance between the highest and lowest value.
Example: 12 17 21 23 24 24 25 26 29 31
Range = 12–31
Interquartile range is the part of the range that covers the middle 50% of the data.

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