Fortunately, the data is already arranged in ascending order, which is a requirement when we're looking for quadrants and the IQR. There are 9 data points, where 9 is an odd number, so the middle data point, 23, is the median.
We must now find Q1 and Q3. To the left of 23 we have 13, 14, 17, 18. Take the median of these four points: It is the average of 14 and 17, or 15.5.
Similarly, find the mediation of 27, 28, 31, 34; it is the average of 28 and 31, or 29.5.
The IQR is the difference between Q3 and Q1; here, that difference is 29.5 - 15.5 = 14.
