Answer
a). $R/4$
b). $3micro-ohm$
Work Step by Step
a). The resistance of two equal parts is $R/2$.
When these are connected in parallel, the equivalent resistance is $R/4$.
b). The resistance of 3 equal parts is $R/3=9micro-ohm$
When these 3 parts are connected in parallel,
the equivalent resistance = $9micro-ohm/3=3 micro-ohm$
