Calculating simple average and stdev

Hi All,

I have simple problem regarding calculating average across different sheets of a work book. I have data on three different costs in AC9,AC10,AC11. The location is same in all the sheets. I am trying out the following formula.

=AVERAGE(Sheet1!AC9,Sheet2!AC9,Sheet3!AC9,Sheet3!AC9)
=STDEV(Sheet1!AC9,Sheet2!AC9,Sheet3!AC9,Sheet3!AC9)

Is there anything wrong in this formula.

Any suggestion is welocme

Thanks,
Upananda

you have 4 arguments in your functions, it should be 3

=average(a1,b1,c1)

finds the average of the numbers in a1 b1 and c1