premise: A man in a black shirt and jeans appears to be working on some piping system. hypothesis: A plumber attempts to correct a problem with the plumbing system.
neutral: The first sentence doesn't say what type of man he is nor what type of piping system it is. Sentence 2 goes into more detail and used the descriptors plumber and plumbing. It also tells us that he isn't just working on the system, he's correcting a problem with it.