The interquartile range is 12.5.
We first find the median. To do this, order the data from least to greatest and find the middle value:
72, 80, 81, 84, 92, 92, 94, 95
There are 8 data values. The median is between 84 and 92:
(84+92)/2 = 176/2 = 88
The median splits the data into two halves. The lower quartile is the median of the lower half; this is between 80 and 81:
(80+81)/2 = 161/2 = 80.5
The upper quartile is the median of the upper half; this is between 92 and 94:
(92+94)/2 = 186/2 = 93
The interquartile range is found by subtracting these:
93-80.5 = 12.5