Its started after World War 2 because after a lot of issues arose between the US and USSR. They had a mutual distrust with each other stemming from the way the US had perceived the USSR as an illegitimate part of the international community. The way the USSR perceived the US as people who intervened in everyone's business and had amounted weapons.
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)
