The puzzle is impossible to solve without more information. We see only 2 dimensions. The 3rd dimension gives depth (not visible) that can vary between reservoirs. Without this dimension, pipe size and knowing the rate of flow there is no way to determine the answer.
Oops, 4 is blocked
I got it wrong, because like so many puzzles, our minds move too quickly and make assumptions which do not exist - and do not look at very small, but important details. In this case, with the pathways leading to each cup.
Too easy!!! #9
If this is considered a brain teaser the world is doomed.
#9 as it will be the first cup to receive coffee based upon the tube opennings, location of the spickets, and an equal or larger tube size if the coffee enters all tubes evenly and freely. But the first cup to be filled is mine as I am not going to waste the money and time trying to prove anything that has no need. I leave that to people that follow twitter or Facebook. So the best way is not to play. How about a nice game of chess?
rwood
Not Enough Coffee!
9
9. Look at the levels of the pipes. On the left, the coffee would start draining off to the left before reaching the level of the pipe on the right. Then, becausse the pipe going to cup 4 is blocked, the coffee will drain into the 9 cup. Unless you pour very fast it’s unlikely that any coffee will get to cup 5.
Five is the only one not blocked.
Thank goodness for those laser instruments...
If you were to switch cups #7 and #5, then #7 would fill first.
Assuming we’re still subject to gravity it’s #4.
#5 is the only one that can fill. The others all have closed off line that will keep them from getting coffee.
4, 7, and 9 are all blocked. Looks like #5.
#5
If those graphic blockages are intentional, then #5. If they weren’t meant to be there, #4.
4, 9, and 7 are blocked off, so it’s 5. Eventually.
It appears there are blockages on #4, #7 and #9, leaving #5 as the only possibility.