Question

7th one please solve....

Answer 1

equivalent resistance of n resistances connected in series
R = nr
equivalent resistance of n resistances connected in parallel
R' = n/ r
so
ratio = R/R'= nr/n/r
= r^2

Answer 2

Series combination:
Total Resistance
                     Rp = R₁ + R₂ + R₃ +.....n 
                           = n Rₐ                        as all resistors are equivalent.
 
Parallel combination:
Total Resistance 
                   1/Rq = 1/R₁ + 1/R₂ + 1/R₃ ..... 1/n
                      Rq = Rₐ/n                      as all resistors are equivalent.

Then ratio = Rp/Rq = n Rₐ/Rₐ/n
                                = n²

:) Hope this Helps !!!