PROBLEMS AND PUZZLES
10 Trees
| There are 10 trees spaced out
equally along my street with one at each end. If I run at a steady speed from one end of the street, I can reach the 8th tree in just 8 seconds. How long would it take me to run down the whole street at the same pace? |
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Electric Clock
|
Joe Slow has an electric 12-hour clock. One evening there
was a power cut from 11pm until 11.19 pm. |
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Two Doors
| There are two doors. Behind one is safety, behind the other is certain death. There are two guardians of the doors, one is known to always tell the truth. The other always lies. You have one question to ask to find out which door is safe to go through. What question do you ask? |  |
Night Crossing
| There are four people on one side of a bridge
in the middle of the night. They only have one torch between them and
the all have to get acrosss the bridge within 17 minutes. However, only
a maximum of two people may cross at one time, and the torch must be always
in the posession of one of the people crossing the bridge. All the people
walk at different speeds, but any pair crossing must walk at the slowest
of the two speeds. The people's speeds are as follows: Person A takes 1 minute to cross Person B takes 2 minutes to cross Person C takes 5 minutes to cross Person D takes 10 minutes to cross How do you get all people across in that time frame? |
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Egg Boiling
| You are a cook in a remote area with no clocks or other way of keeping time other than a 4 minute eggtimer and a 7 minute eggtimer. You do have a stove however with water in a pot already boiling. Somebody asks you for a 9 minute egg, and you know this person is a perfectionist and will be able to tell if you undercook or overcook the eggs by even a few seconds. What is the least amount of time it will take to prepare the egg? |  |