Averaging cells in multiple worksheets

[ColleenMarie47]

I am creating a report with 75 different survey results and I am trying to find the averages of each of the answers. I am working on the formula and I keep getting errors. Here is what I have (I'll spare you all 75 and only input 10)...

=AVERAGE(‘Book1’!E8,‘Book2’!E8,‘Book3’!E8,‘Book4!E8,‘Book5’!E8,‘Book6’!E8,‘Book7’!E8,‘Book8’!E8,‘Book9’!E8,‘Book10’!E8)

Can someone please let me know what I am doing wrong?

 

[Aladin Akyurek]

Create two new sheets, first and last. Place all of the relevant sheets, Book1, etc. between first and last. Now invoke:

=SUM(first:last!E8)/COUNT(first:last!E8)