Re: total duration column
As far as I know about MS Project, it will calculate the duration of the summary task as the number of working days between 20th May through 28th May because according to the task details mentioned above it overlaps from 21-May through 25-May. Though there are 6 days from 20th to 25th May but I’ll count only 4 days as there is a Saturday and Sunday non working days. If you have resources assigned to the first task who has Saturday or Sunday as a working day, I would like to ask whether you want the sum of the work, not the sum of the durations?
- You can have Project sum durations if you choose to given my comments above. Add an custom duration field (Duration1) and customize the field with the formula [duration]. Set the option for group or summary rows to sum.
I hope this helps. Let us know how you get along.
Re: total duration column
Yes, you are correct. Assuming the default standard calendar, note that the duration of your first task is not 5 days but 4 - the 20th, 21st, 24th, and 25th. Since Sat and Sun the 22nd and 23rd are non-working days, they don't count in the duration.