Q:

Calculated field based on sum and count of other field

I have a dataset like this:
Segment   Organisation name   nr of visitors
A         {name}              3
A         {name}              7            
B         {name}              20                  
B         {name}              20
B         {name}              10
B         {name}              10
C         {name}              8
C         {name}              8
C         {name}              8
C         {name}              6

I have a pivot table with three columns, where values are displayed as percentage:
Segment   Count of organisations   Sum of visitors
A         20%                      10%
B         40%                      60%
C         40%                      30%

I want to add a third column which does sum of visitors% divided by count of org.%. 
Segment   Count of organisations   Sum of visitors   Leverage
A         20%                      10%               0.5        
B         40%                      60%               1.5
C         40%                      30%               0.75

Using a calculated field I can't seem to do this. Is it possible to have this as a field in the pivot table?

A:

Although this is a workaround, you can add another column with the below formula and add that column in pivot table as Summarize values by Average.
Formula: =(SUMIF([Segment],[@Segment],[nr of visitors])/SUM([nr of visitors]))/(COUNTIF([Segment],[@Segment])/COUNTA([Organisation name]))
Screenshot below:

