I wasn't able to quite get there, but maybe this can give some ideas.
I used rolling sums (in my case, just check the numbers did rolling 2 months)
of Passed and Total Exams and divided them for the Rolling Performance.
with table calculation settings as shown below.
Unfortunately, I couldn't get as a last column, but as a first column.
Please see workbook attached in the Forum thread.
275188rolling.twbx 25.0 KB
Swaroop you are a genius Brilliant solution. Thank you
If you have time and chance i have another problem related to rolling average calculation if you can help Count number of students according to Rolling Average performance