Saturday, July 29, 2017

'The Slowest Race' Brain Teaser

An Arab sheik is old and must will his fortune to one of his two sons. He makes a proposition. His two sons will ride their camels in a race, and whichever camel crosses the finish line LAST will win the fortune for its owner. During the race, the two brothers wander aimlessly for days, neither willing to cross the finish line.

In desperation, they ask a wise man for advice. He tells them something; then the brothers leap onto the camels and charge toward the finish line.

What did the wise man say?

The slowest is the winner in the race

This is what he said! 

Winning 'The Slowest Race'

Why was wise man asked? 

The wise man asked the brothers to switch camels. Now every brother tried

hard to make other brother's camel a winner! 

Trick to be fair in the slowest race
     Wise Man's Advice

Being Alive After Lift Crash Landing? - Puzzle

A lift is on the ground floor. There are four people in the lift including me.When the lift reaches first floor, one person gets in and three people get out.The lift goes up to the second floor, 2 people get out 6 people get in.It then goes up to the next floor up, no-one gets out but 12 people get in. Halfway up to the next floor up the lift cable snaps, it crashes to the floor.

Everyone else dies in the lift. How did I survive?

Living alive after lift crash landing
This is how did I! 

Escape from Crash Landed Lift

This was the incident. 

Read carefully once again, in journey from 1st to 2nd floor there are only 2 

people in the lift. At 2nd floor, 2 people get out that means it includes me   

as well. This is how I survived.

Escape from crash landing lift

Selecting The Barbershop

A man is driving South to Florida for a vacation. On the way, he realizes that he needs a haircut, so he stops in a small town along the way. He asks one of the residents where he can find a barbershop, and the resident tells him that there are only two barbers in town, one in the north part of town and one in the south. The man visits the north barber, and finds that the barbershop is messy and the barber himself has a bad haircut. He then visits the south barber, who has a clean barbershop and a good haircut

Which barbershop to choose?

However, the man decides to return to the north barber for his haircut. Why does he do this?

This is why he does so! 

Reason To Choose The North Barbershop

Here is the question! 

Since there are only 2 barbershops in town each barber has to go to each other for their haircut. So barber with good haircut must had it from the other barber at the north. Obviously, the man choose him to get a nice look. 

Hence he must chosse the north barbershop.

Friday, July 28, 2017

Bird's Journey From Train To Train

Suppose distance between SECUNDERABAD & CST is 1000 KM. Railway tracks are in straight lines with no curves in between.

A train with uniform speed of 100 kmph departs from CST at 9:00 AM. Same day on same track other train from SECUNDERABAD departs at 10:00 AM with uniform speed of 80 kmph.

A bird sitting on engine of train that departed from CST starts traveling toward the SECUNDERABAD & after touching the engine of that train travels back to CST train. A bird repeats this until trains collide.

How much distance the bird traveled & how many times did it travel to & fro? 

Distance covered by bird in the journey?

Click for the answer! 

Distance Travelled By The Bird

Here is the question! 

Let's divide answer in 2 parts.

1.Finding distance traveled by the bird.

The SECUNDERABAD train is one hour late till then CST train covers 100 km.

Hence effective distance is 900 km

Total speed of approach = 100 + 80 kmph

Total distance covered = 900 km

Time passed before trains collide = 900/180 = 5 Hours

Speed of bird = 120 kmph

Distance covered in 5 hours by bird = 120 * 5 = 600 km

Distance covered in first hour by bird = 120 km

Total distance = 600 + 120 = 720 km

2. Finding how many times bird traveled back & forth.

1st travel -

Total speed of approach = 120 + 80 = 200 kmph

Total distance to be covered = 900 km

Time required to meet each other = 900/200 = 4.5 Hours.

2nd travel -

Distance traveled by CST train in 4.5 hours = 100 x 4.5 = 450km

Distance traveled by SECUNDERABAD train in 4.5 hours = 80 x 4.5 = 360 km

Distance between 2 trains = 900 - (450+360) = 90 km

Time left for collision is 5 - 4.5 = 0.5 hrs.

So bird ends up with 1 complete round.

Calculation of Distance Travelled By The Bird

How To Reach The Island?

Abhijeet wants to reach an island which is in the middle of the river. The island is 30 feet from the edge of the river. As shown in the picture below he got two wooden planks about 29 feet each.

Any trick to reach the island?
          How to reach there?

How can Abhijeet reach the island? 

This is how he reached!


Trick To Reach The Island.

Here is the task! 

A picture is worth thousands of words.

Reaching to the island with given resources
  Finally, reached there!

Wednesday, July 26, 2017

The Honest and Dishonest Guards

You’re in a room with two doors. There’s a guard at each door. One door is the exit, but behind the other door is something that will kill you. You’re told that one guard always tells the truth and the other guard always lies. You don’t know which guard is which. You are allowed to ask one question to either of the guards to determine which door is the exit. 

What question should you ask?

Finding the correct exit door!
Exit door

Here is that question! 

Question to Find The Exit Door

What was the situation? 

What if I tell you that you have to ask only one question to anyone & choose the opposite door? Yes, be patient & read further.

Ask anybody this question.

"What would other guard answer if I ask him which one is exit door?"

Now there are two possibilities.

1. If the guard is truth telling then he knows other guard would lie & point the door leading towards the death. So he will point that door.

2. If the guard is lying then he knows other truth telling guard would have pointed right door.But in order to lie, he would point to opposite door! 

Finding the correct exit door!

Six Glasses in a Row

There are six glasses in a row. The first three are full of orange juice, and the next three are empty. By moving only one glass how can you make them alternate between full and empty?

Move 1 to make it alternate
Make it alternate!

Here is solution!

Alternate Glasses in a Row

What was the riddle? 

All you need to do is pour 2nd glass into 5th one! It is as simple as that

one! See Below!

Making it alternate
To make it alternate!

On a Mission of Fishing

Two fathers and their two sons go fishing together. They each catch one fish to take home with them. They do not lose any fish, and yet when they arrive at home they only have three fishes. 

How can this be?

How this could be possible?

This is how it can be! 

Three Generation On Mission

What's the matter? 

There are grandfather, father & grandson. So there are 2 fathers viz. father & grandfather while there are 2 sons viz. father & grandson! Three generations on the mission.

Total 3 persons on mission
Three Generations

Tuesday, July 25, 2017

Which Coin is Counterfeit?

You are given eight coins and told that one of them is counterfeit. The counterfeit one is slightly heavier than the other seven. Otherwise, the coins look identical. Using a simple balance scale, how can you determine which coin is counterfeit using the scale only twice?

Finding fake coin using balance
Identify The Fake Coin

This is how it can be found! 

To Identify The Counterfiet Coin!

Why it was asked to? 

1. Make a group of 3 coins each. Weigh these groups against each other.

2. If both groups weigh equal then weigh remaining 2 against each other. Heavier coin would be easily identified.

3. If one of group is heavier, then take out coins of this group.The counterfeit coin is among them.

4. Now weigh 2 of 3 coins of this group against each other.

5. If both are equal then obviously third one is counterfeit.

6. If one of them is heavier then obviously that one is counterfeit. 

The Safest Room - Lateral Thinking

A murderer is condemned to death. He has to choose between three rooms. The first is full of raging fires, the second is full of assassins with loaded guns, and the third is full of lions that haven't eaten in 3 years.

Which room is safest for him?

Which one is the safest room?
The Safest Room

Which one;find it here! 

The Safest Room - Lateral Thought

What was the puzzle?

If murderer has a little brain then he would choose the third room 

straightaway. How lions can stay alive for 3 years without eating anything? 

A murderer with no brain

"He is my son"

A man and his son are in a terrible accident and are rushed to the hospital in critical care. The doctor looks at the boy and exclaims "I can't operate on this boy, he's my son!"

How could this be?

Here is that lateral thought! 

A Doctor Can Be Mother

Why it was required? 

The doctor is mother of that son!

Monday, July 24, 2017

Visual Illusions Psychology

Which monster looking bigger? The one which is chasing the other? Right?

Monster optical illusion
Bigger Vs Smaller

Now look at this. What's your take now?

Monster optical illusion demystefied
Equal Heights

Both are of same size. A 3D tunnel built around deceives your visual system & totally changes how it perceive things.

Now take a look at this. Are these straight lines or not? Definitely not! Right?

Curved lines optical illusion
Straight or Curved

But you are totally wrong! Have a look at this.

Curved lines optical illusion demystefied
Only Straight Lines

Again white & black checks surrounded in certain disorder changes how you perceive things.  

Checker Shadow illusion

Which square is darker here; A or B?

Checker Shadow illusion
A is darker or B

The A appears darker than B here. But that's not the reality. Both shares equal levels of brightness & gray levels. A printer would you same ink to print those squares. 

Checker Shadow illusion demystefied
Equally Darker

What's challenge to visual system here?

The task given to your visual system here is to determine the color of the object & here it is gray level. But shadow of cast plays here big role. The square under shadow reflecting less light than the one is not in shadow. Visual system need to do several tricks to compensate that shadow effect & determine the exact color of the square under shadow.

What tricks visual system uses?

1. Local contrast : Irrespective of shadow, a lighter check surrounded by more lighter checks is perceived as a check with more average lightness & vice versa. In the figure, the light check in shadow is surrounded by darker checks. Thus, even though the check is physically dark, it is light when compared to its neighbors. The dark checks outside the shadow, conversely, are surrounded by lighter checks, so they look dark by comparison.

2. Shadows often have soft edges while paints (here checks) have sharp edges. The visual system tends to ignore gradual changes in light level, so that it can determine the color of the surfaces without being misled by shadows. In this figure, the shadow looks like a shadow, both because it is fuzzy and because the shadow casting object is visible.

3. The "paintness" of the checks is aided by the form of the "X-junctions" formed by 4 abutting checks. This type of junction is usually a signal that all the edges should be interpreted as changes in surface color rather than in terms of shadows or lighting.

Conclusion :

The effect illustrates success rather than failure of our visual system. The illusion asking our visual system to act as a light meter; but it's definitely not built for it. What's the success of our visual system here is it breaks the information into meaningful components & then perceive different aspects of objects.

Courtesy : Wikipedia

Sunday, July 23, 2017

Water Measurement With 2 Buckets - Puzzle

You have two buckets. One holds exactly five gallons and the other three gallons. How can you measure exactly four gallons of water into the five gallon bucket?

Assume you have an unlimited supply of water and that there are no measurement markings of any kind on the buckets.

Water Measurement With 2 Buckets - Puzzle
How to measure 4 gallons?

Click here to know how it could be done? 

Water Measered Using 2 Buckets - Puzzle Cracked

What was the challenge? 

Method 1 :

1. Fill up the 3 gallons bucket & pour into 5 gallons bucket.

2. Again fill the gallon bucket & once again pour it into 5 gallons bucket. After completely filling 5 gallons bucket there will be 1 gallon left in 3 gallons bucket.

3. Empty 5 gallons bucket.

4. Pour that 1 gallon into 5 gallons bucket. Now fill up 3 gallons bucket. We have 4 gallons of water now 1 in 5 gallons bucket & 3 in 3 gallons bucket.

Method 2:

1. Fill up 5 gallons bucket & pour it into 3 gallons bucket. 2 gallons would remain in 5 gallons bucket.

2. Pour that 2 gallons of water into 3 gallons bucket. Now only space for 1 gallon left in 3 gallons bucket.

3. Again fill up 5 gallons bucket & pour into 3 gallons bucket containing 2 gallons of water left. So only 1 gallon can be poured & 4 gallons would be remaining in 5 gallons bucket. 

3 Switches And 1 Light Bulb

You are standing outside a closed door. On the other side of the door is a room that has a light bulbs in it. The room is completely sealed off from the outside. It has no windows and nothing can get in or out except through the door. On the outside of the room there are three light switches that controlling light bulb on the other side of the door.

Your assignment is to determine which light switch controls that light bulb. You are allowed to enter the room only once and once you come out, you must be able to state with 100% certainty which light switch controls which light bulb.

3 Switches And 1 Light Bulb
Which controls bulb?

What should you do? 

The Control Switch of Bulb

What's the matter? 

Turn ON first light switch, wait a few minutes, then turn it OFF and turn ON the second light switch. Now go to the room, if bulb is ON then second switch is controlling it. If it's OFF, then touch it & if it feels warm then first switch which you had switched ON for a while. And if it isn't warm then definitely third switch controlling the light bulb.

Steps to find the switch controling the bulb

The Dog in Trouble

A completely black dog was strolling down main street during a total blackout affecting the entire town. Not a single streetlight had been on for hours. As the dog crosses the center of the road a Buick Skylark with two broken headlights speeds towards it, but manages to swerve out of the way just in time.

How could the driver see the dog to swerve in time?

The driver saved the dog
How did I survive?

Not that much difficult! 

Time When Incident Took Place

What was the incident?

The incident happened during day time! Everything else scripted to deceive you!

The driver could save do as it was bright sunny day
Day Time

Saturday, July 22, 2017

The Bus Driver

You are the bus driver. At your first stop, you pick up 29 people. On your second stop, 18 of those 29 people get off, and at the same time 10 new passengers arrive. At your next stop, 3 of those 10 passengers get off, and 13 new passengers come on. On your fourth stop 4 of the remaining 10 passengers get off, 6 of those new 13 passengers get off as well, then 17 new passengers get on. What is the color of the bus driver’s eyes?

What is color of bus driver's eyes?

 Find answer here! 

Color of Bus Driver's Eyes

What's the question? 

Answer is hidden in very first statement! What's color of your eyes then?

What is Color of Bus Driver's Eyes?

The Missing Dollar

Three travelers register at a hotel and are told that their rooms will cost $10 each so they pay $30. Later the clerk realizes that he made a mistake and should have only charged them $25. He gives a bellboy $5 to return to them but the bellboy is dishonest and gives them each only $1, keeping $2 for himself.

So the men actually spent $27 and the bellboy kept $2.What happened to the other dollar of the original $30?

Story of the missing dollar

Here it is found! 

The Story of Dollar That Wasn't Lost

How it was lost? 

All you need to think on the behalf of travelers to simplify things around.

Initially they spent $30 for the stay. Now these $30 distributed into 2 parts viz. 25 & 5 by clerk.  Out of 5, travelers received only 3 that means now they have spent $27 only. Out of 27, clerk had 25 & bellboy took 2! Trying to add bellboy's 2 in 27 is pointless but the base of this quiz!

The dollar itself wasn't missing at all!

Time to Fill Up The Tank

There are 2 taps to fill a big tank; one is bigger & other is smaller. A bigger alone can fill up the tank in 5 hours less than smaller tap can alone. Both taps together take 6 hours to fill up the tank.

How many hours required separately for smaller & bigger taps to fill up the tank?

Time required by bigger & smaller taps

Click here for answer!

Hours Needed By Each Tap

What was the question? 

Let x be hours required for bigger tap then smaller needs x + 5

In 1 hour bigger fills 1/x & smaller fills 1/(x+5) part of the tank. Together both take 6 hours to completely fill the tank. So,

1/x + 1/(x+5) = 1/6

6(x + 5 + x) = x^2 + 5x

x^2 - 7x - 30 = 0

(x-10) (x+3) = 0

x + 3 = 0 gives x = -3 which is not possible as x represents hours.

So x - 10 = 0 gives x = 10.

Hence for a bigger tap 10 hours & for smaller tap 10 + 5 = 15 hours required to fill up the tank!

Friday, July 21, 2017

Permutations or Combinations or Common Sense?

You have 12 black socks and 12 white socks mixed up in a drawer. You’re up very early and it’s too dark to tell them apart. What’s the smallest number of socks you need to take out (blindly) to be sure of having a matching pair?

Permutations or Combinations or Common Sense?

To know what it is click here! 

It is Common Sense not Permutaions nor Combinations!

Question is here!

You need only 3 attempts.

Let's say on first draw we get BLACK socks. In next draw, if we get BLACK then we have matching pair immediately. But if in second draw, it's WHITE then we have to go for third draw. 

On a third draw, if it's BLACK then we have pair of BLACK socks ; one came from first draw & other from third one!

On the other hand, if we get WHITE on third draw then we have pair of WHITE socks ; one we got from second & other from third.

It is Common Sense not Permutaions nor Combinations!

Same logic can be applied if WHITE comes in first draw.

Magical Number of Mangoes

Once a man collected few mangoes from a tree. Another man came & all mangoes are distributed among themselves but still 1 left. Third man came & mangoes redistributed but still 1 left. Fourth man came but still 1 left after redistribution. Fifth & sixth man came but still 1 left after re sharing. Finally, when 7th man came all mangoes distributed with no left.

How many mangoes they had?

Mangoes that 7 men had

Skip to answer! 

Finding The Magical Number

What was the teaser? 

We need to first find LCM of 2,3,4,5 & 6. It's 60. Had there been only 6 men then 61 would have been right answer. But on arrival of 7th man all mangoes distributed. So we need to find such number which is divisible by 7 & that number - 1 is divisible by 60.

Smallest such a number is 301. So they had 301 mangoes!

Number of mangoes those 7 men had

Thursday, July 20, 2017

Checking Available Networks In All Phones

This I used to check available networks in the region before purchasing new SIM. I had found this in my first feature phone! 

1. Go to the SETTING.

2. Select PHONE.

3. Enter into NETWORK.

4. Change Operator selection to MANUAL.

5. Wait till phone scans all available networks.

6. Restore Operator Selection to AUTOMATIC otherwise it would keep asking to choose network if you go out of range for a moment.

Network setting all phones
Network Coverage

For smartphones,

1. Go to the SETTING.


3. Enter into MOBILE NETWORK.


5. Change Operator selection to MANUAL.

6. Wait till phone scans all available networks.

7. Restore Operator Selection to AUTOMATIC otherwise it would keep asking to choose network if you go out of range for a moment.

A Tiger, A Goat & A Bundle Of Grass

A man is walking down the village road with a tiger, a goat and a bundle of grass. Soon he arrives at the river bank where there is one tiny boat that can carry him and another animal or grass at a time. 

Here is the problem: Left alone, the tiger will eat the goat. And similarly, the goat will eat the grass bundle. How is he going to take all three across the river safely?

Crossing the river puzzle
Cross The River

What should he do? 

Crossing a river with tiger, goat and grass

What is situation?

1. First he need to carry a goat across the river. Tiger won't eat a bundle of grass.

Safely crossing the river

2. Then he should take a tiger (or a grass bundle) across the river.

Safely crossing the river

 3. And get goat again back with him.

Safely crossing the river

  4. Now he should leave a goat behind & take a grass bundle (or a tiger) with him across the river.

Safely crossing the river

5. Finally he has to take the goat across the river in last round.

Safely crossing the river

How Many Animals Are Going Towards River?

One rabbit saw 6 elephants while going towards river.

Every elephant saw 2 monkeys are going towards river.

Every monkey holds one parrot in their hands.

Now tell me how many animals are going towards river.

Number of animal that rabbit saw
How Many I Saw

How many? Click here!