Statistical questions are unlike mathematical questions. On the math site, a question will quickly be closed if it is not immediately clear what it means and what it is asking. All other questions on that site might as well be textbook questions--there is really no basis for distinction, not even the level of sophistication.
Our community has learned to work within the SE framework to help people articulate the questions they come with. These questions typically are vague, ill-formed, use non-technical language, and often are laden with inherent contradictions and misunderstandings. It is remarkable that we can elicit an answerable question from most of these posts--and that makes our site uniquely valuable.
In this context, a question that is quoted from a textbook, test, or homework set is not the norm, for two salient reasons:
It usually has been clearly and precisely framed in technical language. It requires little or no context to understand and often needs only routine application of purely mathematical operations or elementary statistical thinking for its solution--all of which likely have been illustrated many hundreds or thousands of times in similar threads that vary only in minor details.
It is almost never a real world problem, which is specifically the kind of problem people are invited to pose on this site. The two-minute tour states:
Get answers to practical, detailed questions. Focus on questions about an actual problem you have faced.
(Emphasis added.)
The second point is dispositive: it suggests that the artificial, unrealistic, naive kinds of questions typically posed as homework and tests really don't belong here at all. Perhaps we should redirect them all to the math site, but because we share an interest in the statistical interpretation, we not only tolerate them here, we even welcome them when they invite clear, illuminating, clever, and well-articulated solutions.
self-study
is not a different word for "homework" but a broader class of question that includes homework. $\endgroup$