Answer with Explanation:
Let r be the resistance of short piece of copper wire.
Resistance of copper wire=R=
Resistance is directly proportional to length.
If a wire has greater resistance then,the wire will be greater in length.
Therefore,resistance of long piece of wire=7r
Total resistance of copper wire=Sum of resistance of two piece of wires


ohm
Resistance of long piece of wire=
Resistance of short piece of wire =
Resistivity of wire and cross section area of wire remains same .
Let L be the total length of wire and L' be the length of short piece of wire.
We know that
=

Where K=
=Constant
Using the formula



Length of short piece of wire=L'=
Length of long piece of wire=
% of length of short piece of wire=
%
The resistance of the short piece=
The resistance of the long piece=