the thing is the bubble in there is smthin u dont want - its like a handicap or its jus tht smthin went rong wen makin the rod and ths bubble ended up in it -- so they're asking u the maximum area of this useless bubble so tht the rod dsnt break (hope th idea is clear)
so if the force applied is 1.9x10^3 N
the maximum stress (above which it'll break) is 9.5x10^8
since stress=froce/area
max stress= force/minimum area of rod
so ur min area of rod ends up being = 2x10^-3
the rod is already 3.2x10^-3
so the difference must be th max area of the bubble
subtract the two u end up with 1.2x10^-3
