I am trying to convert monthly data into quarterly data. So, I am
trying to average the numbers from each month composing the quarters,
and then pick-up from the following month. I guess this is better
explained in a formula. The formulas for two consecutive rows should
be:

=AVERAGE(Monthly!C2:C5)
=AVERAGE(Monthly!C6:C9)

So, the first number of the second row should be the next one after
the first row started and they will always add 4 numbers (rows).

But, if I try to get excel to fill in the data, I get (which is not
what I want):

=AVERAGE(Monthly!C2:C5)
=AVERAGE(Monthly!C3:C6)

This is quite a long spreadsheet, so it would be really great if I
could automate the process. I am thinking I need to use OFFSET, but I
don't know how to exactly. Could you please help me?

Thank you very much,
David Santos

P.S.: By the way, my thesis is due in about 20 hours, so this a very
time-sensitive matter :)