QUARTILES –
The observations which divide the whole set of observations into four equal parts, are known as quartiles.
Lower Quartile (on First Quartile) -
If the variates are arranged in ascending order, then the observation lying midway between the lower extreme and the median is called the lower quartile, or First quartile, to be denoted by Q₁.
Upper Quartile (or Third Quartile) -
If the variates are arranged in ascending order, then the observation lying midway between the median and the upper extreme is called the Upper Quartile or Third Quartile, to be denoted by Q₃
Middle Quartile –
The middle quartile is the median, denoted by Q₂.
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