AverageIf

[Noz2k]

I want to work out the average of (column F/column G), when column A starts with the letters "Mon"

can't seem to get it to go,

Just to give more of an idea, the most recent formula I tried which was

=AVERAGE(IF(LEFT(Wallboard!A2:A272188,3)="Mon",Wallboard!F2:F272188/Wallboard!G2:G272188,0))

entered as an array

 

[anglais428]

There's bound to be a better way, but if you insert another column before column A (so this now becomes Column A) and enter =left(B1,3) and autofill. You can then use
=AVERAGEIF(A:A,"Mon",F:F)/AVERAGEIF(A:A,"Mon",G:G)

 

[anglais428]

Again, not brilliant but:

=AVERAGEIF(A:A,"*Mon*",f:F)/AVERAGEIF(A:A,"*Mon*",G:G)