Given set :
154,109,137,115,152,140,154,178,80,103,126,126,137,165,165,129,200,148.
Rewrite the given data set from least to highest values.
80, 103, 109, 115, 126, 126, 129, 137, 137, 140, 148, 152, 154, 154, 165, 165, 178, 200.
Recall that a data point is an outlier if it is over 1.5 times the IQR below the first quartile or 1.5 times the IQR above the third quartile.
We know that
The upper half of the data set is
{137, 140, 148, 152, 154, 154, 165, 165, 178, 200}
The number of data in the set is even.
There are two middle terms in this upper half of the given set. That are 154 and 154.
The lower half of the data set is
{80, 103, 109, 115, 126, 126, 129, 137, 137, 140}
The number of data in the set is even.
There are two middle terms in this lower half of the given set. Which are 126 and 126.
Substitute known values in the IQR formula.
We get IQR=28.