Why does the "Unanswered Questions" tab show questions that have answers?
The Unanswered Questions tab shows questions that have no answers with a positive score nor an accepted answer. (That includes questions with no answers at all.)
@Joel and @Pollyanna, your answer and comment explain the logic behind the behavior, but the unaddressed fact remains that the title of the tab says "Unanswered". Which intuitively means "having received no answers". Agreed, it makes sense and is useful to refine the criteria for the category. But it's confusing to the newcomer, who is still trying to intuitively build a mental model of the concepts and relationships on the web site, to have a label "Unanswered" that appears to label things that have "1 answer" on them. Without questioning the reasoning or the mechanics behind the criteria for this category, it would still save a lot of us newbies confusion if the "Unanswered" label were changed to reflect what it actually means.
Like @EBGreen said, the label could be changed. And/or add tooltips / explanatory text that explain the criteria you just mentioned, without having to go hunt for it. In fact, it would be a good entry for the SO FAQ. The problem has befuddled me, and I've seen it typed in by two others. I expect that for each of us three there are untold numbers who have never bothered to enter a formal question about it.
Sorry for making this an answer rather than a comment, but I keep seeing this question being raised, and people answering the question but not doing anything to alleviate the problem. And the problem would be very easy to fix, it seems to me.
The reason why is that it's very common to get an answer to a question that doesn't actually provide the information requested. (People might provide an incorrect or incomplete answer, or might provide an answer that really should be a comment).
The assumption is that if a answer can get a positive vote, then it's good enough that the question can be considered "answered" (even if the user has not accepted it).
I just asked this question as well, but got closed as a dup of this one (see https://meta.stackexchange.com/questions/83756/tagged-page-shows-answered-questions-but-title-says-unanswered/83757#83757)
I still think this is a bug, but active users probably aren't seeing it.
As a user who had never been to the tagged page before, it loaded with a set of questions which included both answered questions (ie those with accepted answers) and unanswered questions (those with answers but not accepted).
BUT the page title said
Unanswered 'tagname' questions. This was at odds with the page content.
I was able to reproduce this repeatedly, with different tags.
I got an answer which suggested that maybe I was looking at the unanswered tab without realising it. This answer was wrong because I could see that was looking at answered questions. Nevertheless, I clicked on the unanswered tab to see what was different (naturally it was very different).
Now the key point: Subsequent to clicking on that link, I am no longer able to reproduce the bug. I cannot get back to a position where I see a combination of answered and unanswered questions but the title states 'unanswered'.
This is why I think it is a bug, and also why no-one who has spent much time on the site can reproduce it.
[EDIT] NOTE: My question that was marked as a dup has now been deleted. But on re-reading this question, I don't think mine was actually a dup of this one. This question is just about confusion about what is an unanswered question on the unanswered page; mine was about the title showing 'unanswered' when you weren't on the unanswered page. I don't really know what to do now.