Find Standard Deviation, Do items fall in or out of Range?

I have the following column data:

Column A: Location Names
Column B: Category Codes of the locations (i.e. "A - G")
Column C: Page Volume counts (i.e. 45,000)
Column D: To be populated by results from #3 below

I want to investigate any ideas YOU have that could help do the following:

1. Calculate the "mean", or "Average" of all the page volume counts for all locations in each specific category code (i.e. the average for all "C" locations)
2. Determine the Standard Deviation for each category (i.e. the standard deviation for the "A" group, "B" group, etc)
3. Finally, I need to place in Column "D" next to each location an indicator ("+", "-" or "OK") showing if that location's Page Volume is either higher than, lower than, or inside of the standard deviation range for the category.

Thanks in advance for your ideas!

One way to skin this cat would be have columns to the right with IF logic, if yes set the value to value in column C, if no set to "", repeat for each category. at the top or just below then you can use STDEV, AVERAGE, etc on the column. As for column D, You can then use an HLOOKUP across the STDEV result, to find the categories Stand deviation and compare it to its colomn C. My answer is a little cryptic, let me know if you get the drift. I would also use conditional formatting to alert on column D.

Good luck.