Hello Lance,
We went a looked at the code, and are not convinced that the calculation is correct (or meaningful). The calculation is supposed to be:
For each shipment:
((Number of shipments*Avg days)+Days for this shipment)/(Number of shipments + 1)
and then increment the shipment count.
However, that's not what it's doing which explains why you are having trouble getting to the number displayed on the screen.
We will correct the code for Inventory 9.3A (or change it to something else if anyone cares to suggest a better calculation).