How do i find the domain and the range of the function

Note that the graph shows 8 dots with associated x-values 1 through 8.  The domain is the set of integers {1, 2, 3, 4, 5, 6, 7, 8}.  The range is the set of all y-values associated with this domain, a bit harder to read off the graph.  One by one, I will approximate the y-value associated with each x value and present these 8 y-values as the range:  {7.5, 9, 12, 15. 18, 22, 23}.