Here's an example. We'll test the last set of data: 10, 15, 16, 16, 18, 19, 21, 25. The median is the average of the 2 middle data points: (16+18)/2 = 17. So far, so good, since the diagram shows a median of 17. First Quartile: find the median of 10, 15, 16, 16; it is the average of 15 and 16, which comes to 15.5. Third quartile: find the median of 18, 19, 21, 25. It's 20. Does the graph show this? No. The First Quartile in the graph is 15, not 15.5 (but this is not very far off). The Third Quartile in the graph is 20, which matches. So, the fourth set of data might be an answer.
You must check out the other 3 data sets in the same manner. Pick the set that is most closely illustrated by the diagram.
