The Challenge Ahead of New Manager

In a wood-cutting factory, five large sawing machines stand in a windowless room. Each machine has an on/off switch attached, there being no doubt as to which switch controls which machine.

Outside the door to the room are five back-up on/off switches, one for each machine inside. The power for each machine must first pass through the back-up switch, and then the machine switch before reaching the saw.

The problem is, the new manager cannot decide how these back-up switches match with the machines inside the room. One day, the manager's brother visits. The manager takes him inside the sawing room where all five machines are at work and explains the problem. The brother announces that he intends to leave the room and that when he returns he will be able to match correctly the five switches outside the room to the five machines inside. The brother works alone, cannot see the machines from outside the room and solves the problem purely by operating switches. 

How is it possible?

Read how brother managed to do it! 

Genius Moves by Brother of Manager!

What was the challenge?

Suppose you are the brother of that manager & have accepted the challenge. 

For sake of convenience, we will name switches inside the room operating machines as an 'operating switches' & those which are outside the room as a 'back up switches'.

Though windowless, we assume that operating sound of machine(s) can be heard from outside room but can't see which machine(s) is (are) in operating condition. 

Here is what you should do!

1. Let's label the machines which we are going to keep ON as ACTIVE & others as INACTIVE. 

2. Turn off operating switches of 2 machines so that there are three machine ACTIVE and two are INACTIVE inside the room.

3. Go outside and now your task is to find the 3 back up switches controlling 3 active machines inside the room.

4. You have to switch off three switches in all possible combinations. There are 10 such possible combinations (5C3) of 3 controlling switches out of 5.

5. If 0 represents OFF position and 1 represents ON position then you should try all possible below combination. 

11000
10100
10010
10001
01100
01010
01001
00110
00101
00011

6. There will be exactly one combination in which all three ACTIVE machines  will be OFF & there will be no sound coming out of the room. The three switches having value of 0 are controlling ACTIVE machines while other 2 must be controlling INACTIVE machines.

7. Still we don't know the exact switch operating the each machine. Label 3 switches controlling ACTIVE machines as A, B and C & those controlling INACTIVE machines as D & E. 

Allow some time to cool down all those ACTIVE machines.

8. Now, turn on 2 switches A & B and keep switch E ON. Machines connected to A and B will start working.

9. After a while, turn off the switch B and go inside the room. 

10. The machine which is still operating must be controlled by back up switch A.

11. Touch other 2 which were labelled as ACTIVE & check which has got warmer.

12. The machine which is warmer must be controlled by back up switch B.

13. And since we didn't turn on the switch C (after giving time all to cool down), the machine having normal temperature must be controlled by the switch C.

14. Remember, we had turned off operating switches of INACTIVE machines initially. And before entering into room again we have turned on switch E. 

15. Now, turn on operating switch of one of the INACTIVE labelled machine. 

If the machine starts working it must be connected to the switch E & other to the switch D. And if the machine doesn't start working it must be connected to D & other to E. 

This way, you will find every back up switch located outside the room controlling operating switch of each machine inside the room.

 

Who is The Opposite Gender?

Sam, Alex, Charlie, and Jordan are related. 

One of them is the opposite gender from the other three. Here are some facts:

1. Charlie's only son is either Sam or Alex.

2. Jordan's sister is either Alex or Charlie.

3. Jordan is either Sam's brother or Sam's only daughter.

Who is the opposite gender from the other three?

Know here the name of the person with opposite gender! 

Charlie is The Opposite Gender!

What was the puzzle?

Given Facts : 

Sam, Alex, Charlie, and Jordan are related


1. Charlie's only son is either Sam or Alex.
2. Jordan's sister is either Alex or Charlie.
3. Jordan is either Sam's brother or Sam's only daughter.

ANALYSIS : 

1] As per (3), if Jordan is Sam's only daughter then Jordan must not have any sister. But this is opposite to the fact (2). Therefore, Jordan must be Sam's brother. Jordan is male for sure. 

2] If Jordan's sister is Alex (female), then as per (1), Charlie's only son (male) must be Sam. But as concluded above [1], Jordan is Sam's brother so how Charlie can have only one son? Therefore, Jordan's sister is Charlie who is obviously female.

3] If Jordan is Sam's brother [1] and Charlie is Jordan's sister then it's clear that Jordan, Sam and Charlie are siblings. And now as fact (1) suggests Charlie's only son must be Alex (male).

CONCLUSION : 

ALEX, JORDAN and SAM are male and CHARLIE is the opposite gender i.e. female. 

  

A Visit To Grandmother's Home!

A father wants to take his two sons to visit their grandmother, who lives 33 kilometers away. His motorcycle will cover 25 kilometers per hour if he rides alone, but the speed drops to 20 kph if he carries one passenger, and he cannot carry two. Each brother walks at 5 kph. 

Can the three of them reach grandmother’s house in 3 hours?

Do you think it's impossible? Click here!

Planning Journey Towards Grandmother's Home

What was the challenge in the journey?

Yes, all three can reach at grandmother's home within 3 hours. Here is how.

Let M be the speed of motorcycle when father is alone, D be the speed of motorcycle when father is with son and S is speed of sons.  Let A and B are name of the sons.

As per data, M = 25 kph, D = 20 kph, S = 5 kph.

1. Father leaves with his first son A while asking second son B to walk. Father and A drives for 24 km in 24/20 = 6/5 hours. Meanwhile, son B walks (6/5) x 5 = 6 km.

2. Now father leaves down son A for walking and drives back to son B. The distance between them is 24 -6 = 18 km.

3. To get back to son B, father needs 18/(M+S) = 18/(25+5) = 18/30 = 3/5 hours & in that time son B walks for another (3/5) x 5 = 3 km. Now, son B is 6 + 3 = 9 km away from source where he meets his father. While son A walks another (3/5) x 5 = 3 km towards grandmother's home.

4. Right now father and B are 24 km while A is 6 km away from grandmother's home. So in another 24/20 = 6/5 hours father and B drive to grandmother's home. And son B walks further (6/5) x 5 = 6 km reaching grandmother's home at the same time as father & brother B.

In this way, all three reach at grandmother's home in (6/5) + (3/5) + (6/5) = 3 hours.

In this journey, both sons walks for 9 km spending 9/5 hours and drives 24 km with father taking (6/5) hours. Whereas, father drives forward for 48 km (24 km + 24 km) in (6/5) + (6/5) hours and 15 km backward in 3/5 hours. 
  

Initial Amount in Wallet?

On the festival of Raksha Bandhan (holy festival where brother-sister relationship celebrated), Mayank decides to visit his 3 sisters. He takes certain amount with in his wallet & goes to first sister. While without his notice first sister puts equal amount of money as in wallet. After tying rakhi, Mayank gifts her Rs.2000. Now he moves to second sister. While Mayank takes a breakfast, the second sister secretely doubles the money that was in Mayank's wallet. Again after tying rakhi, Mayank gifts her Rs.2000. At third sister's home, while he enjoys delicious lunch cooked by his sister, third sister doubles money in his pocket. Once again after tying rakhi, Mayank gifts third sister Rs.2000.Now there were Rs.5000 in his wallet.

How much amount Mayank had taken while leaving his home?

How much amount? Find it here! 

Simple Calculation for Initial Amount

What was the puzzle? 

We need to go backward to get the answer.

3. At third sister's home he had 2000 + 5000 = 7000. So before visit he had 7000 / 2 = 3500.

2. At second sister's home he had 3500 + 2000 = 5500. This 5500 were doubled from his existing 2750 by her second sister.

1. At first sister's home he had 2750 + 2000 = 4750. His first sister had added 4750 / 2 = 2375 to his wallet in which there were Rs. 2375 already.

So Mayank took Rs. 2375 with him in his wallet while he left home.

However, Mayank must had idea of that his sisters added money to his wallet without his attention.

 

The Man in The Photograph

A man is looking at a photograph of someone. His friend asks who it is.

The man replies, 'Brothers and sisters, I have none. But that man's father is my father's son'.
 
Who is in the photograph?

Know here the relationship between! 

Source 

Relation With The Man in Photograph

What was the incident? 

The person in photograph is the man's son. Since the man doesn't have any 

brothers or sisters, the statement my father's son is himself. A shortened 

version would be this man's father is myself; so he is the father of the man in

the picture.