A possible solution
Create this table in, say, X1:Z4
X Y Z
[TABLE="width: 173"]
<TBODY>[TR]
[TD="class: xl65, width: 81, bgcolor: transparent"]Q1-2012
[/TD]
[TD="class: xl66, width: 75, bgcolor: transparent, align: right"]01/01/2012
[/TD]
[TD="class: xl66, width: 75, bgcolor: transparent, align: right"]03/31/2012
[/TD]
[/TR]
[TR]
[TD="class: xl65, bgcolor: transparent"]Q2-2012
[/TD]
[TD="class: xl66, bgcolor: transparent, align: right"]04/01/2012
[/TD]
[TD="class: xl66, bgcolor: transparent, align: right"]06/30/2012
[/TD]
[/TR]
[TR]
[TD="class: xl65, bgcolor: transparent"]Q3-2012
[/TD]
[TD="class: xl66, bgcolor: transparent, align: right"]07/01/2012
[/TD]
[TD="class: xl66, bgcolor: transparent, align: right"]09/30/2012
[/TD]
[/TR]
[TR]
[TD="class: xl65, bgcolor: transparent"]Q4-2012
[/TD]
[TD="class: xl66, bgcolor: transparent, align: right"]10/01/2012
[/TD]
[TD="class: xl66, bgcolor: transparent, align: right"]12/31/2012
[/TD]
[/TR]
</TBODY>[/TABLE]
A
[TABLE="width: 56"]
<TBODY>[TR]
[TD="class: xl66, width: 75, bgcolor: #c5d9f1"]Quarter
[/TD]
[/TR]
[TR]
[TD="class: xl65, bgcolor: transparent"]Q2-2012
[/TD]
[/TR]
[TR]
[TD="class: xl65, bgcolor: transparent"][/TD]
[/TR]
[TR]
[TD="class: xl66, bgcolor: #c5d9f1"]Dates
[/TD]
[/TR]
[TR]
[TD="class: xl67, bgcolor: transparent, align: right"]01/01/2012
[/TD]
[/TR]
[TR]
[TD="class: xl67, bgcolor: transparent, align: right"]01/11/2012
[/TD]
[/TR]
[TR]
[TD="class: xl67, bgcolor: transparent, align: right"]01/21/2012
[/TD]
[/TR]
[TR]
[TD="class: xl67, bgcolor: transparent, align: right"]01/31/2012
[/TD]
[/TR]
[TR]
[TD="class: xl67, bgcolor: transparent, align: right"]02/10/2012
[/TD]
[/TR]
[TR]
[TD="class: xl67, bgcolor: transparent, align: right"]02/20/2012
[/TD]
[/TR]
[TR]
[TD="class: xl67, bgcolor: transparent, align: right"]03/01/2012
[/TD]
[/TR]
[TR]
[TD="class: xl67, bgcolor: transparent, align: right"]03/11/2012
[/TD]
[/TR]
[TR]
[TD="class: xl67, bgcolor: transparent, align: right"]03/21/2012
[/TD]
[/TR]
[TR]
[TD="class: xl67, bgcolor: transparent, align: right"]03/31/2012
[/TD]
[/TR]
[TR]
[TD="class: xl68, bgcolor: yellow, align: right"]04/10/2012
[/TD]
[/TR]
[TR]
[TD="class: xl68, bgcolor: yellow, align: right"]04/20/2012
[/TD]
[/TR]
[TR]
[TD="class: xl68, bgcolor: yellow, align: right"]04/30/2012
[/TD]
[/TR]
[TR]
[TD="class: xl68, bgcolor: yellow, align: right"]05/10/2012
[/TD]
[/TR]
[TR]
[TD="class: xl68, bgcolor: yellow, align: right"]05/20/2012
[/TD]
[/TR]
[TR]
[TD="class: xl68, bgcolor: yellow, align: right"]05/30/2012
[/TD]
[/TR]
[TR]
[TD="class: xl68, bgcolor: yellow, align: right"]06/09/2012
[/TD]
[/TR]
[TR]
[TD="class: xl68, bgcolor: yellow, align: right"]06/19/2012
[/TD]
[/TR]
[TR]
[TD="class: xl68, bgcolor: yellow, align: right"]06/29/2012
[/TD]
[/TR]
[TR]
[TD="class: xl67, bgcolor: transparent, align: right"]07/09/2012
[/TD]
[/TR]
[TR]
[TD="class: xl67, bgcolor: transparent, align: right"]07/19/2012
[/TD]
[/TR]
[TR]
[TD="class: xl67, bgcolor: transparent, align: right"]07/29/2012
[/TD]
[/TR]
[TR]
[TD="class: xl67, bgcolor: transparent, align: right"]08/08/2012
[/TD]
[/TR]
[TR]
[TD="class: xl67, bgcolor: transparent, align: right"]08/18/2012
[/TD]
[/TR]
[TR]
[TD="class: xl67, bgcolor: transparent, align: right"]08/28/2012
[/TD]
[/TR]
[TR]
[TD="class: xl67, bgcolor: transparent, align: right"]09/07/2012
[/TD]
[/TR]
[TR]
[TD="class: xl67, bgcolor: transparent, align: right"]09/17/2012
[/TD]
[/TR]
[TR]
[TD="class: xl67, bgcolor: transparent, align: right"]09/27/2012
[/TD]
[/TR]
[TR]
[TD="class: xl67, bgcolor: transparent, align: right"]10/07/2012
[/TD]
[/TR]
[TR]
[TD="class: xl67, bgcolor: transparent, align: right"]10/17/2012
[/TD]
[/TR]
[TR]
[TD="class: xl67, bgcolor: transparent, align: right"]10/27/2012
[/TD]
[/TR]
[TR]
[TD="class: xl67, bgcolor: transparent, align: right"]11/06/2012
[/TD]
[/TR]
[TR]
[TD="class: xl67, bgcolor: transparent, align: right"]11/16/2012
[/TD]
[/TR]
[TR]
[TD="class: xl67, bgcolor: transparent, align: right"]11/26/2012
[/TD]
[/TR]
[TR]
[TD="class: xl67, bgcolor: transparent, align: right"]12/06/2012
[/TD]
[/TR]
[TR]
[TD="class: xl67, bgcolor: transparent, align: right"]12/16/2012
[/TD]
[/TR]
[TR]
[TD="class: xl67, bgcolor: transparent, align: right"]12/26/2012
[/TD]
[/TR]
</TBODY>[/TABLE]
Select A2
Data > Data Validation
Allow: List
Source:$X$1:$X$4
Select all the dates (A5:A41 in the example above) being the first cell (A5 in the example above) the active cell, ie, the one that is not shaded after the selection
Home > Conditional Formatting > New Rule > Use a formula to determine which cells to format
insert this formula
=$A5=MEDIAN($A5,VLOOKUP($A$2,$X$1:$Z$4,2,0),VLOOKUP($A$2,$X$1:$Z$4,3,0))
Format button
Fill --> yellow (for example)
Ok, Ok
Done!
M.