Handshakes at Party
Posted on May 11, 2014
(Last modified on August 7, 2020)
| 1 minutes
| Kinshuk Chandra
Problem I was at a party with MS one evening where he got bored and started keeping track of the number of handshakes made by people. A person was called “odd person” if he made an odd number of handshakes, otherwise he was called “even person”. After some time MS said to me, “Hey AD, do you know that there are an even number of odd persons?” I replied, “Big deal, MS.
[Read More]Key Exchange Puzzle
Posted on May 11, 2014
(Last modified on August 7, 2020)
| 1 minutes
| Kinshuk Chandra
Problem Jan and Maria have fallen in love (via the internet) and Jan wishes to mail her a ring. Unfortunately,
they live in the country of Kleptopia where anything sent through the mail will be stolen unless it
is enclosed in a padlocked box. Jan and Maria each have plenty of padlocks, but none to which the
other has a key. How can Jan get the ring safely into Maria’s hands?
[Read More]Russian Roulette
Posted on May 11, 2014
(Last modified on August 7, 2020)
| 2 minutes
| Kinshuk Chandra
Problem Lets play a game of Russian roulette. You are tied to a chair and can’t get up. Here is the gun , six chambers all empty. Now I put two bullets in the gun and I put these bullets in the adjacent chambers. I close the barrel and spin it. I put the gun to your head and pull the trigger. Click and the slot was empty. Now before we start the interview I want to pull the trigger one more time , which one do you prefer , that I spun the barrel first or that I just pull the trigger ?
[Read More]Cut a rectangular Cake
Posted on May 11, 2014
(Last modified on August 7, 2020)
| 1 minutes
| Kinshuk Chandra
Problem
How do you cut a rectangular cake into two equal pieces when someone has already taken a rectangular piece from it?
The removed piece an be any size or at any place in the cake. You are only allowed one straight cut.
Solution
Join the centers of the original and the removed rectangle. It works for cuboids too!
References
Rope Around EARTH
Posted on May 11, 2014
(Last modified on August 7, 2020)
| 1 minutes
| Kinshuk Chandra
Problem A fool wants to tie a rope around the earth. So he buys a rope of 40,000 KM and ties it around the world. His neighbour, also a fool, wants to do the same only he wants the rope on sticks 1 meter above the ground.
How much more rope does he need?
Solution The outline of a circle is 2*PI*r. If you want a rope that is one meter above the ground rnew=r+1.
[Read More]THE DEVIL & COLORED HATS
Posted on May 11, 2014
(Last modified on August 7, 2020)
| 2 minutes
| Kinshuk Chandra
100 people find themselves at the gates of hell. The devil tells them that they’ll have a chance to go to heaven instead, but first they’ll have to play a game.
The devil is going to line them all up in a straight queue, each person facing the back of the next person in line. The order of people in this line will be randomly chosen when the game starts.
[Read More]Black and white hats - Who knows what he is wearing
Posted on May 11, 2014
(Last modified on August 7, 2020)
| 2 minutes
| Kinshuk Chandra
There are four man standing in front of a firing-squad. Two of them (nr.1 & 3) wear a black hat and two of them (nr.2 & 4) wear a white hat. They are all facing the same direction and between nr.3 and nr.4 stands a brick wall (see picture). So nr.1 can see nr.2 & 3, nr.2 sees nr.3, nr.3 sees only the wall and nr.4 doesn’t see a thing. The men know that there are two white and two black hats.
[Read More]Prisoners and Boxes
Posted on May 11, 2014
(Last modified on August 7, 2020)
| 3 minutes
| Kinshuk Chandra
You are the janitor at a prison with 100 prisoners locked in separate, soundproof and windowless cells.
You watch one day as the warden brings the prisoners out to a central room where there are 100 boxes laid out, labeled 1 through 100. He hands each prisoner a slip of paper and a pen, and asks everyone to write their name on their slip and hand it back to him. All the prisoner’s have different names.
[Read More]Prisoner and lightbulb
Posted on May 11, 2014
(Last modified on August 7, 2020)
| 2 minutes
| Kinshuk Chandra
Problem There is a prison with 100 prisoners, each in separate cells, which are sealed off, soundproof and windowless. There is a lobby in the prison with a lightbulb in it. Each day, the warden will pick one of the prisoners at random (even if they have been picked before) and take them out to the lobby. The prisoner will have the choice to flip the lightbulb switch if they want.
[Read More]Travelling MONK
Posted on May 11, 2014
(Last modified on August 7, 2020)
| 1 minutes
| Kinshuk Chandra
A monk leaves at sunrise and walks on a path from the front door of his monastery to the top of a nearby mountain. He arrives at the mountain summit exactly at sundown. The next day, he rises again at sunrise and descends down to his monastery, following the same path that he took up the mountain.
Assuming sunrise and sunset occured at the same time on each of the two days, prove that the monk must have been at some spot on the path at the same exact time on both days.
[Read More]