The interquartile range is \(17 - 7 = 10\). (Sometimes we are asked for the semi-interquartile range . This is half of the interquartile range and in this case would be 5) ...

The interquartile range (IQR) is therefore 18 - 4 = 14. You will notice that the fact there is an outlier in this data (60) which has had no bearing on the calculation of the interquartile range.