Average Cell Range based on Day of Week

[kyddrivers]

I am trying to average the values of a range of cells based on the day of the week.

The spreadsheet is setup as follows:

[TABLE="width: 500"]
<tbody>[TR]
[TD]Column A:[/TD]
[TD]Column B:[/TD]
[/TR]
[TR]
[TD]1/4/15[/TD]
[TD]23.90%[/TD]
[/TR]
[TR]
[TD]1/5/15[/TD]
[TD]14.39%[/TD]
[/TR]
[TR]
[TD]1/6/15[/TD]
[TD]4.62%[/TD]
[/TR]
[TR]
[TD]1/7/15[/TD]
[TD]5.71%[/TD]
[/TR]
[TR]
[TD]1/8/15[/TD]
[TD]18.32%[/TD]
[/TR]
[TR]
[TD]1/9/15[/TD]
[TD]31.62%[/TD]
[/TR]
[TR]
[TD]1/10/15[/TD]
[TD]11.28%[/TD]
[/TR]
[TR]
[TD]1/11/15[/TD]
[TD]13.13%[/TD]
[/TR]
[TR]
[TD]1/12/15[/TD]
[TD]29.40%[/TD]
[/TR]
[TR]
[TD]1/13/15[/TD]
[TD]8.57%[/TD]
[/TR]
[TR]
[TD]1/14/15[/TD]
[TD]14.44%[/TD]
[/TR]
[TR]
[TD]1/15/15[/TD]
[TD]33.21%[/TD]
[/TR]
[TR]
[TD]1/16/15[/TD]
[TD]3.33%[/TD]
[/TR]
[TR]
[TD]1/17/15[/TD]
[TD]14.81%[/TD]
[/TR]
</tbody>[/TABLE]

What I am attempting to do is Average the cells in column b if the date in column a is a Sunday.

I have tried using a simple If(weekday(A1:A14)=1, Average(B1:B14), "") and this returns a #value error, but I don't think it would give me the answer of 18.52% I am looking for.

I have tried AverageIf(B1:B14, Weekday(A1:A14)=1) and I get #div/0!

Any help is greatly appreciated.

Thanks in advance!!

 

[svendiamond]

This might be an overly complicated formula but it works:

=SUMPRODUCT(--(WEEKDAY(A2:A15)=1),B2:B15)/SUMPRODUCT(--(WEEKDAY(A2:A15)=1))

 

[Aladin Akyurek]

Control+shift+enter, not just enter:

=IFERROR(AVERAGE(IF(WEEKDAY($A$2:$A$15,2)=7,$B$2:$B$15)),"")

where 7 = Sunday.

 

[kyddrivers]

Thank you for the quick and excellent solutions!!