Quartiles and Interquartile Range

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Example: a website's response time over ten visits was 120, 135, 140, 150, 155, 160, 170, 180, 210 and 450 milliseconds. Where is the middle half of the times, and are any of them outliers? Change the values to work out your own case.

Values x_i At least four, separated by spaces or commas.

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What each term means

Interquartile Range (IQR): The width of the band holding the middle half of the data. It measures spread without being swayed by extreme values, and defines outliers: anything more than 1.5 · IQR beyond the box.
Third Quartile (Q₃): The value below which 75% of the data lie. It is the right edge of the box in a boxplot.
First Quartile (Q₁): The value below which 25% of the data lie. It is the left edge of the box; the median, Q₂, lies between Q₁ and Q₃.