I am using the following to calculate the mean per row where the ID's are the same.
=IF(A4=A3,"",SUMIF(A:A, A4,E:E )/COUNTIF(A:A, A4))
Column A contains my ID's, Column E contains the paid amounts. This works except for the fact that if there are 2, 3, 4 matching ID's it will not populate the...