It occurs to me that your requirement is .... a less than useful selection for a visualization.
All the points on the "scatterplot" are always going to be along a straight line. (In practice it may "jig" a little, but in reality it's mathematically straight.) If your max duration is (for example) 20 days, then the far left point possible is 19 days ago, and the left edge and top edge of the chart both represent a ticket aged 20 days. Basically, duration and start date/time are the same measurement, so a graph that compares them is a waste of electrons.
Here's a run-anywhere code to generate random test data and show you a graph, assuming that your max duration was 20 days.