Which straw fills the cup first?

[lost in melb.]

 

6 is blocked at the bottom. Why 2? (2 was the most common answer)

 

If all the blocks are real it must be 2 or 3. The liquid will flow out of the hole into either 2 or 3.

2 if the liquid flows quickly, like a waterfall.

3 if slowly and it hugs the outside of the straw