You have the misfortune to own an unreliable clock. This one loses exactly 24 minutes every hour. It is now showing 3:00am and you know that is was correct at midnight, when you set it. The clock stopped 1 hour ago, what is the correct time now?
6:00am: since the clock is losing 24 minutes every hour, for every real hour that has passed, the clock will only show 36 minutes. Since the clock shows 3:00am, we know that 180 clock minutes have passed. This therefore equals 300 real minutes and hence 5 hours. The clock stopped 1 hour ago and the time must now be 6.00am. QED.
There is a frog, dead in the middle of an island. If he swims north, the distance to the mainland is 2 meters. If he swims south, the distance to the mainland is 3 meters. If he swims east or west, the distance is 4 meters. Which way does he swim?
You are standing on the top one of two solid metal pillars. They are both exactly one kilometer apart from each other and they both stand one kilometer high. There is absolutely nothing around these pillars, but you have one small twig, one small rock and an unlimited supply of rope. Usuing only the materials named, how can you get from the top of the pillar that you are on to the top of the other pillar?
The twig and the rock were simply distractions used to divert you from the real answer. Forget I ever mentioned them. All you need to do is fill the space between you with enough rope that it makes a pile so big that you can walk across it to the other pillar (remember I said you had an unlimited supply of rope).