A murderer is condemned to death. He has to choose between three rooms. The first is full of raging fires, the second is full of assassins with loaded guns, and the third is full of lions that haven't eaten in 3 years. Whichroom is safest for him?
Marble walls as white as milk, lined with skin as soft as silk, in a fountain crystal clear, a golden apple will appear, there is no key to this stronghold, yet theives break in and steal the gold. What is it?
I have a clock in my house, on the wall.
On a summer's day I forgot to wind it and it stopped. Then I went to visit a friend who had a watch that was always right on time. After I stayed for a bit, I went home, made a simple alteration and set the clock just right.
Now how did I do this when I had no watch on me to tell how long it took me to come back from my friend's place?
Before I left, I wound the wall clock. Upon my return, the amount of change that I could see in the clock is how long it took to go to my friends place and come back, adding to that the time I spent there, which I know because the clock at my friend's place is accurate.
Subtracting the time of the visit from the time I was absent from my house, and dividing by 2, I obtained the time it took me to return home. I added this time to what my friend watch showed when I left, and set the sum on my wall clock.
The key to this riddle is realizing that you do not have to pull the emergency switch in the first room, the entrance, and so that room will not lock down. You can leave it, and then return to it and go out the other door. And indeed this is exactly what you need to do so you can hit all 16 rooms and end in the exit room.
Once you know to leave and reenter the first room, there are eight possible solutions to travel through all the rooms and end at the exit. Because the first room is clear, you can backtrack through it to get back on the right track and pull the emergency switch in every room, saving the world from agonizing death by ancient virus.