If you can quantify what "defying the normal trend" means, then you
could use an array formula (entered with Ctrl-Shift-Enter) like
=AVERAGE(IF(intrend(range),range))
where intrend(range) is an array formula that returns TRUE or FALSE for
each cell in range, depending on whether that cell should be included in
the average or not.

Jerry

Vinaya wrote:

Hi,

I need to calculate average of 3 months. However, if any particular
month is defying the normal trend, that month should be ignored while
calculating the average.

For Eg:

Jan Feb Mar Average
2 2 2 2
4 4 6 4
2 1 2 2

Is this possible?

Regards,
Vinaya.