Correct Answer - `(1)/(n^(2))`
To get minimum posibale resistance, the resistors are to be connected in parallel .Then the connected minimum resistance is given by
`(1)/(R_(min)) = (1)/(r ) + (1)/(r ) + … n "times" = (n)/(r ) or R_(min) = r//n`
For maximum position resistance, the resistors are to be conneted in series. Then the combined maximum resistance is given by
`R_(min) = r+ r + .... "times" =nr`
`:.(R_(min))/(R_(min)) = (r//n)/(nr) = (1)/(n^(2))`