AVERAGEIF

Returns the average of all cells in a range based on a condition

Syntax:

AVERAGEIF(range, criteria, average_range)

range is the cells you want to look at.

criteria is the condition you want to test the range against.

average_range is optional, and is the actual cells is used if specified, otherwise range is used.

Example:

If A1:A10 includes the numbers of 1 to 10:

AVERAGEIF(A1:A10, "<5")

returns 2.5