Answer
a). series, $60ohm$
b). parallel, $5.5ohm$
Work Step by Step
a). To get maximum equivalent resistance, we should connect them in series
And equivalent resistance $=10+20+30=60ohm$
b). To get minimum equivalent resistance, we should connect them in parallel,
And equivalent resistance is given by :-
$\frac{1}{R_{eq}}=\frac{1}{10}+\frac{1}{20}+\frac{1}{30}$
Eq. R= $5.5 ohm$
