Automatic Invigilation duty list in excel

Hai
I would like to request a help on creating an invigilation duty list
My requirement

An automatic duty list in excel which randomly and evenly selects teachers according to students number or no of rooms
No of rooms should be calculated automatically based on our input like students per invigilator.

Its highly appreciable if you can help to solve my problem.

=SMALL(IF(ISNA(MATCH(ROW($A$1:INDEX($A:$A,$A$1)),C$3:C3,)),ROW($A$1:INDEX($A:$A,$A$1))),RANDBETWEEN(1,$A$1-COUNT(C$3:C3))) CSE
press F9 for new selection

Thank you very much for your valuable time and effort to solve my issue.
If you don't mind could you pls explain the steps you done on the sheet as well as how to insert name of teachers instead of numbers.
I am not an expert in excel. just an intermediary or an advanced beginner.

Thank you once again for your help.

=INDEX(Data!$A:$A,help!C4+1)

Thank you very much for your wonderful support