Welcome to the forums!
Since you have the processing time as well as the 1st and 3rd quartiles in your data, you may want to look into Dual Axis charts. Here's a quick read: Dual Axes
See the image below. Basically, you'll use two different measures and 1) change the second to use a Dual Axis, and 2) change the mark type for each measure as desired. The different mark types will now overlay the same pane in the visualization.
Another thing to consider is that Tableau has the ability to show quantiles. To enable this, right click the Y axis and then "Add Reference Line." The distribution option will give you the ability to show the quartiles however you want.
If you get stuck or have any additional questions you might want to consider posting a packaged workbook (using mocked up data if necessary) and I'd be happy to work through specific issues.