I have many columns of information. And I want to average the information in
one of the columns based on a certain value appearing in another column. I
am using Excel 2002. In example below I would like to average the numbers in
column 3 if its associated number in column 1 is 1.

1 Y 345
2 N 423
3 N 235
1 Y 745
3 Y 437
1 Y 584
2 N 373
1 Y 436

so I have a few formulas I have tried. First:
=IF(C4:C873=1,AVERAGE(M4:M873))
the problem is I return False as the value.
Second:
=AVERAGE(IF(C4:C873="1",M4:M873))
and zero is returned