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Riddle Me This

by Elizabeth Roman

Riddle #1.
There are 4 men who want to cross a bridge. They all begin on the same side.

You have 17 minutes to get all of them across to the other side. It is night. There is one flashlight. A maximum of two people can cross at one time. Any party who crosses, either 1 or 2 people, must have the flashlight with them. The flashlight must be walked back and forth, it cannot be thrown etc. Each man walks at a different speed.

A pair must walk together at a rate of the slower man’s pace.

Man 1: 1 minute to cross.
Man 2: 2 minutes to cross.
Man 3: 5 minutes to cross.
Man 4: 10 minutes to cross.
For example, if Man 1 and Man 4 walk across first, 10 minutes have elapsed when they get to the other side of the bridge. If Man 4 returns with the flashlight, a total of 20 minutes have passed, and you have failed the mission.

See how quickly you can solve this!

p.s. The flashlight cannot shine a long distance. No one can be carried, etc. (This is a straightforward problem. There are no tricks.)


Riddle #2 - The Cannibal's Puzzle
This question is asked at job interviews at Microsoft.

While exploring the jungle three scientists get caught by a tribe of cannibals. Begging for mercy, they finally are granted one last chance to save their lifes:

Each of them is bound to a stake, so that one scientist can see the backs of the other two before him, the one in the middle can only see the back of the one in front, while the latter can’t see anybody. They are now shown five colored feathers, among which there are three white ones and two black ones. They are then blindfolded and each of them is to put one of the feathers into his hair. Finally they are taken off the blindfolds and posed the question to determine the color of their own feathers.

If only one of them should be able to guess the correct color, all three of them would be released.

Time passes... then the man bound to the foremost stake (who actually can’t see anybody) correctly names the color of his own feather.


What thoughts must have lead to his answer?

have fun.

First Published in Seeds & Stems, bi-monthly publication of the Maryland Apple Corps, PO Box 668, Riderwood, MD 21139-0668.
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