Answer
We can rank the situations according to the charge on the outer surface of the shell:
$(1) = (2) = (3)$
Work Step by Step
In part (a), we found the charge $Q$ on the inner surface of each shell:
(1) $Q = -4q$
(2) $Q = +6q$
(3) $Q = -16q$
We can find the charge $Q'$ on the outer surface of each shell:
(1) $-4q+Q' = 0$
$Q' = +4q$
(2) $+6q+Q' = +10q$
$Q' = +4q$
(3) $-16q+Q' = -12q$
$Q' = +4q$
We can rank the situations according to the charge on the outer surface of the shell:
$(1) = (2) = (3)$
