Average time duration with multiple instances of the same date

Based on the following sample data, I would like to calculate the average total time, as regards to single dates (not only time duration):

Date	In	Out	Total Time
Wed 09/09/2015	09:00	17:00	08:00
Thu 10/09/2015	09:00	11:00	02:00
Thu 10/09/2015	11:00	14:00	03:00
Thu 10/09/2015	14:00	17:00	03:00
Fri 11/09/2015	09:00	17:00	08:00
Sat 12/09/2015	09:00	17:00	08:00
Average			05:20

The current formula that calculates the average in cell "D8", which needs to be modified, is

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The result should be 08:00.
Is it possible to avoid using VBA or adding any columns to calculate totals per date prior calculating the average?
The MS Excel version is 2007.

The spreadsheet can be downloaded here:
example.xls

Any help???

try with this:

=SUM(D2:D10)/(SUMPRODUCT(($A$2:$A$10<>"")/COUNTIF($A$2:$A$10,$A$2:$A$10&"")))

try with this one:

=SUM($D$2:$D$22)/SUM(IF(FREQUENCY(A2:A22, A2:A22)>0,1))

I've test it with split time per day and total time per day (in AVERAGE 2). It gives correct result.

test.xls

To be honest, I have no idea how you could have formula to ignore the blank, or to have Min and Max.
I would suggest to try with pivot table. It will give you automatically sum per date (ignoring blanks), and it will be easier to find the min and max value from that.

test - pivot.xls