What is the interquartile range of the data?
120, 140, 150, 195, 203, 226, 245, 280

Let me rewrite it :(120, 140, 150,) 195, 203,( 226, 245, 280)

1) Find the Median: Since the number of data points are even, the Median will be the average of the terms 195 & 203, that is

Median = (195+203)/2 =199
Now find the Median value of the lower & upper part  (between parenthesis)
Median Lower Part = 140 ==> it's called Q₁
Median Upper part = 245 ==> it's called Q₃
The interquartile range = IQR = Q₃-Q₁ =245 - 140 ==> 105
Remark: The Q₂ is nothing but the central value (in our case it's the median calculated at 199)

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