Premise: "Boys in orange life jackets sitting on raft in water."
Hypothesis: "Boy's stranded overboard on a raft."
Do we know that the hypothesis entailed by the premise? Now, let's be accurate as possible. Some thinking first:
Boys in orange life jackets sitting on raft in water does not imply they are stranded overboard on a raft. So, the answer is it is not possible to tell.