Answer
$$S = \{SSS,SSF,SFS,SFF,FSS,FSF, FFS, FFF\}$$
$A = \{SFS, FSS\}$
$B = \{FFF\}$
Work Step by Step
$S$ represents "success" and $F$ represents: "failure".
The sample space contains all possibilites of outcome; the first interview can result in $S$ or $F$; the same is true for the second and the third.
$$S = \{SSS,SSF,SFS,SFF,FSS,FSF, FFS, FFF\}$$
In the event A, the third interview must be a success; thus, we eliminate: SSF, SFF, FSF, FFF
In SSS and FFS, the third interview is not the second success.
$A = \{SFS,FSS\}$
In the event B, there is no success; thus, the only outcome possible is FFF
$B = \{FFF\}$
