Average Calculated Field on Pivot Table

[adrienne0914]

I am trying to insert a calculated into field my pivot table so that it gives me the average for the last 3 months in the last column. When I use the formula =AVERAGE(Last 3 months), it inserts a formula between each column, rather than giving me an average to the right. I'm sure there is a simple answer, but I struggle with adding formulas to pivot tables.

Sum of Animals	Column Labels
	Last 3 months
Row labels	Feb	Mar	Apr	3 Mo Avg
House Pets	15	123	72
Cats	4	5	7
Dogs	5	100	20
Parrots	6	18	45

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