What does that have to do with solving problems? If you can't do it off the top of your head, a quick search will give you the formula and then you plug it in. Questions like this make me not accept a job offer for a place.
In general I don't like questions like this either, but this particular one seems designed to test your wits if not your memory: if you don't happen to remember the formula, you can quickly derive it. I bet if you said out loud "It's the area of the end circle times the height of the cylinder", you wouldn't have to go any farther.
Yeah, it sounds more like "do you understand the spatial principle in determining volume" more than anything.
No. I said exactly that, and provided the formula for the area of the circle, and was still asked to do the calculation.
Why are trivial questions useful during recruitment?