[CurlyDave]

Seems clear that it's #9, unless I'm missing something...This is actually similar to a problem I had on my P.E. exam some years ago. LOL.

You are missing something. The outlet into #9 is also blocked.

The only cup without a blocked path for the coffee is #5, which has to be the the correct answer -- did you get the question right on the P.E. exam?

[Alberta's Child]

Thanks. I noticed that shortly after my post. I don’t know if I got the right answer on the exam. I passed the exam, so it wasn’t all that important to know. LOL.