First, take into account that the open circle means that the point is not included into the domain and the range. The closed point means that such a point is included into both domain and range.
In this case, althoug there is a open circle, there is another part of the curve on which the y value is included into the path.
Then, the range of the graph is:
ran f = [2,7]
Which is equivalent to all number from 2 to 7.
