Who am I? I'm Zecora. A pleasure, I am sure.
You claim that around Ponyville, you've not seen me before?
I guess that's understandable. My hut's a bit out the way,
I'm visiting the town for official business, I'd say.
You are perhaps acquainted with the one called Pinkie Pie?
If that is so, perhaps you could indulge me? You ask why?
Rumours of your puzzle skills have reached the Everfree,
And your impressive logic, I would rather like to see.
I therefore challenge you to find the answer to my puzzle,
If you're as good as ponies say, this will not leave you muzzled?
I have right here in front of me a bucket filled with potion,
And I do seek to challenge you with quite a curious notion.
The bucket has no markings to determine just how much,
How do you find this out? Not by guessing, not as such.
I filled it to the halfway point to the best of my ability,
But chances are I'm slightly off, speaking of practicality.
It could be slightly fuller, perhaps emptier instead,
Or it may be filled exactly, putting me already ahead.
Using the bucket only, however can you tell
Just how much potion's in there? I hope the answer's well!
Kick the bucket over and now you have an empty bucket
tilt the bucket till water hits the edge,if the bottom is visible its less, just covers it mean half, and completely covered means more
The bucket is cylindre-shaped.
...
...Wait, that's right! One must tilt it, until the liquid is about to spill, then check, if the bottom is visible. If one needs to spill a drop or two in order to adjust the level to be right between the side and the bottom, then the bucket is fuller. If the level is right between after tilting, it's full exactly. And if the bottom can be seen -- it's less full, than Zecora would have liked!
Geometry!