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## **Puzzle**

Started by amit.insan, Jul 04, 2009, 03:46 PM

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#### amit.insan

##### Jul 04, 2009, 03:46 PM
There is a prisoner who is about to be executed. The king decides to give him one last chance to live.

There are 2 doors, the life door and the death door. There is one guard standing by each door. Those two guards know which door is the life door and which is the death door. However, one of them always tells the truth and the other always tells a lie. There is no way you can identify which door is the life door or the death door. There is no way you can distinguish who is the one telling the truth.

The prisoner can only ask one guard one question. Then he needs to choose a door to walk in. If he walks in the death door, then he will be executed. If he walks in the life door, he can have a new life.

He did choose the life door and lived. What was the question he asked? How did he choose the door after he got the answer from one of the guards?

#### Kalyan

#1
##### Jul 04, 2009, 04:12 PM
Hi,

Assume Door A is Life Door, Door B is Death Door

If Guard 1 Is the truth speaking guard, he knows his liar companion will always lie, so will tell him the truth and say his companion will ask him to open Door B.

If Guard 2 is the lie speaking guard, he knows his truthful companion will always tell the truth, so will tell him a lie and say his companion will ask him to open Door B.

Since both of them say "Door B" as the answer, it is evident the other door is the correct one. So the prisoner decides to open Door A and comes out alive.

#### amit.insan

#2
##### Jul 04, 2009, 05:02 PM
hi dear kalyana

the prisoner don't know who will tell lie and who will tell truth.

try again. you can ask any question from the guards.

#### amit.insan

#3
##### Jul 04, 2009, 05:03 PM
puzzle no 2 :

Four people need to cross a rickety rope bridge to get back to their camp at night. Unfortunately, they only have one flashlight and it only has enough light left for seventeen minutes. The bridge is too dangerous to cross without a flashlight, and it's only strong enough to support two people at any given time.

Each of the campers walks at a different speed. One can cross the bridge in 1 minute, another in 2 minutes, the third in 5 minutes, and the slow poke takes 10 minutes to cross. How do the campers make it across in 17 minutes?

#### Karthipc

#4
##### Sep 12, 2011, 03:09 AM

puzzle no 2 :
the guy who can cross the bridge in 1 min will go every time with another one person.ie., with 2 min walking person, 5 min walking person and 10 min walking person.
Now totally
1st time(with 2 min guy)                 -2 min
2nd time(with 5 min walking guy)   -5 min
3 rd time(with 10 min walking guy)-10 min
totally----------------------------------- 17 min(which is equal to light's life time).
** here the trick is the person who can walk in 1 min can walk slowly for 2,5,10 min in order to return the torch for next trip.

#### paresh kothari

#5
##### Jul 14, 2012, 11:57 PM
DEAR Karthipc:
person who cross the bridge in 1 min. will also take 1min. more to come back to his remaining friends.
acc. to u it will become 19 min.

ans.. 1st- 1min speed person will go along 2 min. and will stop at mid way but 2min person will continue and 1min. person would turn light towards the forward. (-2min.)

2nd- now 5 min. person will start and  1min. person help through directing lifgt on path (-5 min.)

3rd- now slow one starts and after midway 1 min. will join him. (-10 min.)

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