How to assign hours to an activity regardless the duration

[Giuseppe1230]

Hello everybody, 
I am having trouble in assigning the right amount of hours in the activities of a project I am working in.
Briefly: 

I have task "1.1" that has lasted 20 days, and now it is 100% complete.

I have to make a report on the macrotask "1", comprehending task 1.1, but when I report the % of completion of the macro, it is heavily influenced by the 160h (20workdays*8h) of the task 1.1, when in fact, it needed 30-40h, even though it has lasted 20 days.

How is it possible to create activities in which the duration is not directly linked to the output of work necessary to complete them? So that, in the report once I put 100% completion, MP calculates 100% of 40h, not of 160h, even though the activity lasted 20 days? 

Thanks in advance 

[#2]

@Giuseppe1230 

Hello Giuseppe.

You can select Task type to "Fixed Duration", ... in the Advanced tab of Task Information, for example.

If you have multiple tasks created with this case, you can insert the Task Type column into the tasks table.

For future tasks, if you want them to be of the Fixed Duration Type, by default, you can set it in File > Options > Schedule > Scheduling options for this project: ...

I hope I've helped.