AVERAGEAVISIBLE

AVERAGEAVISIBLE(rgeValues)
Returns the average value from the visible, non blank cells in a range (including logical values and text).

REMARKS
* This function excludes hidden cells caused by AutoFilter, Grouping or that have been Manually Hidden.
* You can use the built-in AVERAGEA function to include hidden cells.
* You can use the user defined AVERAGEVISIBLE function to return the average value from the visible, non blank cells.
* You can use the user defined AVERAGEVISIBLEIFS function to return the average value from only the visible, non blank cells that satisfy multiple conditions.
* You can use the user defined AVERAGETOP function to return the average from a range of values only considering the top "x" values
* Similar to the user defined functions COUNTAVISIBLE, MAXAVISIBLE and MINAVISIBLE

For instructions on how to add this function to a workbook refer to the page under Inserting Functions