Average of DateTime based on a 10 hour work day

[WallyWallWal]

Hello.  I am having issues calculating the average hh:nn it takes to completed a task.  Image below for assistance in trying to explain:

I have a start datetime of 01/17/23 16:49:00 (hh:nn:ss) and an Completed DateTime of 01/26/2023 16:05:00 (hh:nn:ss).  I need to take into account an 8-hour work day and exclude weekends.  

So if am am looking at this, the time from StartDatetime to CompleteDatetime based on the above example would be 55:16 (hh:mm), with the weekend exclude from this calculation (1/20 & 1/21).  Now lets says I needed to know the average time in hh:nn over the last month that it took one individual to complete each task (assume each row in the StartDatetime column is a task for this example).  How would I go about doing that in a DAX calculation or otherwise?

Basing this off the CompletedDatetime, there were 12 task completed. If it took 507.50 hours (507:30 hh:nn), I should get an average of 42.29 hours (42:17 hh:nn).  How can I get this calculation to work in my favor?

Below is the calculation I am using to get a string for the total, but can't average out a string.  This is where I need help.  Thanks!

Business Hours Time Format =

VAR _WorkStart =

    TIME( 7, 00, 0 )

VAR _WorkFinish =

    TIME( 18, 00, 0 )

VAR _1DayWorkingTime =

    DATEDIFF( _WorkStart, _WorkFinish, HOUR )

VAR _StartDate =

    [StartDate] // Set the start Date column here

VAR _EndDate =

    [InitialTranslationDateCompleted]// Set the End Date column here

VAR _StartDateTime =

    [StartTime] //  Set the start Time column here

VAR _EndDateTime =

    [CompletedTime] //  Set the End Time column here

VAR _DaysBetweenStartFinish =

    ADDCOLUMNS( 'Calendar', "DayN", WEEKDAY( 'Calendar'[Calendar_Date], 2 ) ) // Use the Date table here

VAR _WorkingDaysBetweenStartFinish =

    COUNTX(FILTER(_DaysBetweenStartFinish,

            'Calendar'[Calendar_Date] > _StartDate && 'Calendar'[Calendar_Date] < _EndDate && [DayN] < 6  && 'Calendar'[HOLIDAY_YN]="N"),

           [DayN]) // Sunday and Saturday are weekend days in this calculation //  Set [Holiday = No] to exclude those days from the calculation

VAR _Day1WorkingHour =

    IF(WEEKDAY( _StartDate, 2 ) < 6,

        ( MAX( _WorkFinish, _StartDateTime ) - MAX( _StartDateTime, _WorkStart ) ) * 24,

        0)

VAR _LastDayWorkingHour =

    IF(WEEKDAY( _EndDate, 2 ) < 6,

        ( MIN( _WorkFinish, _EndDateTime ) - MIN( _EndDateTime, _WorkStart ) ) * 24,

        0)

VAR _Duration =

    IF(_StartDate = _EndDate&&WEEKDAY(_StartDate,2)<6,

        MAX(( MIN( _WorkFinish, _EndDateTime ) - MAX( _WorkStart, _StartDateTime ) ) * 24,

            0),

        _WorkingDaysBetweenStartFinish * _1DayWorkingTime + _Day1WorkingHour + _LastDayWorkingHour

    )

VAR _Hour =

    TRUNC( _Duration )

VAR _Minute =

    TRUNC( ( _Duration - _Hour ) * 60 )

RETURN

    _Hour & ":" & _Minute

[lbendlin]

Please provide sample data that covers your issue or question completely, in a usable format (not as a screenshot).
https://community.powerbi.com/t5/Community-Blog/How-to-provide-sample-data-in-the-Power-BI-Forum/ba-...
Please show the expected outcome based on the sample data you provided.

https://community.powerbi.com/t5/Desktop/How-to-Get-Your-Question-Answered-Quickly/m-p/1447523