Premise: "A smiling post office worker proudly shows off his four wheeled mailbag carrier."
Hypothesis: "A snarling postal worker throws his mailbag across the room."
Do we know that the hypothesis entailed by the premise? Now, let's be accurate as possible. Some thinking first:
The worker that proudly shows off his four wheeled mailbag carrier cannot be the same that throws it across the room. So, the answer is no.