A challenging brainteaser shared on X (formerly Twitter) by Daily Quiz and Riddles has stumped 99% of people, with only 1% able to correctly identify which cup will fill up first. The puzzle shows seven cups connected by pipes under a tap, with some pipes blocked and cups containing holes.
At first glance, Cup 4 might seem the obvious answer as it sits at the bottom. However, closer inspection reveals that the pipe connecting Cup 3 and Cup 4 is sealed, preventing water flow. Similarly, Cups 5 and 6 have obstructions in their connecting pipes, ruling them out.
Cup 7 has a hole at the bottom, meaning any water from Cup 2 will simply leak out. The only cup that can actually fill is Cup 3, which is linked to Cup 1 via a lower pipe than Cup 2. Cup 2 is not only accessed via a higher pipe but also connected to leaky Cup 7, so it will never fill.
Reactions on X included comments like “That’s tricky” and “This is cheating, 4 is plugged.” Regular brainteasers are known to sharpen problem-solving skills and cognitive abilities.
