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The Green-Eyed Logic Puzzle

In the green-eyed logic puzzle, there is an island of 100 perfectly logical prisoners who have green eyes—but they don't know that. They have been trapped on the island since birth, have never seen a mirror, and have never discussed their eye color.

On the island, green-eyed people are allowed to leave, but only if they go alone, at night, to a guard booth, where the guard will examine eye color and either let the person go (green eyes) or throw them in the volcano (non-green eyes). The people don't know their own eye color; they can never discuss or learn their own eye color; they can only leave at night; and they are given only a single hint when someone from the outside visits the island. That's a tough life!

One day, a visitor comes to the island. The visitor tells the prisoners: "At least one of you has green eyes." 

On the 100th morning after, all the prisoners are gone, all having asked to leave on the night before. 

The Green-Eyed Logic Puzzle

How did they figure it out?


Here is the solution! 

The Green-Eyed Puzzle Solution


Here is that Puzzle! 

Nobody is going to dare to go the guard unless he is absolutely sure that he is green eyed; otherwise it would be suicidal move.

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For a moment, let's assume there are only 2 prisoners named A & B trapped on island.

On first day, A is watching green eyed B & B can see green-eyed A. But both are not sure what is color of their own eyes. Instead, A(or B) waited B(or A) to escape from island since he is green-eyed. Rather both are sure that other too doesn't know anything about color of own eyes.

On next morning both see each other still on island. Here is what A thinks.


If I was non green-eyed then B would have realized that the person pointed by visitor in his statement ('at least one of you have green eyes') is himself. Hence, B would have realized that he is green-eyed & could have escaped easily. Since B didn't try to escape that means I too must have green eyes.

So A can conclude that he too have green eyes. Exactly same way, B concludes that he too has green eyes. Hence, on next day both can escape from the island.
 

Note that, if the night of the day on which visitor made statement is counted then next day would have 1st morning & 2nd night since visitor's visit. Now since A & B left on 2nd night, we can't see anybody on 2nd morning next day.

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Now let's assume there are 3 prisoners named A,B and C trapped on island.

Let's think from A's point of view as an example.What he thinks.

Let me assume I don't have green eyes.Now each B and C could see 1 green-eyed & other non green-eyed person. But still they don't know color of own eyes.So on that night nobody tries to escape.

On first morning I see both B and C still present there.

Now B can think that if he has no green eyes then C could have concluded that the person pointed by visitor's statement ('at least one of you have green eyes') is C himself (as both A & B are non green-eyed. This way, C would have realized that he is green-eyed.

In a very similar way, B would have realized that he too is green-eyed.

Now both of them could have escaped on that night as they are sure that they are green-eyed.

But on the second morning, I see again both of them are still there. So now I can conclude that I too have green eyes.


If A can conclude then why can't B and C?  So after seeing each other on 3rd day, each of 3 can conclude color of eyes is green. Now on 3rd night they all can escape safely.

This is called as inductive logic.

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If observed carefully, 2 prisoners need 2 nights and 3 prisoners need 3 nights to logically deduce that the each of them is green-eyed.

Hence, 100 prisoners would require 100 nights to absolutely make sure that each of them is green eyed.

That's why on the 100th morning day, there is no prisoner present on island. 


The Green-Eyed Puzzle Solution


Crack 'This' Logic!

IF

1   1   1   1    =  R

2  2   2   2   =  T

3  3   3   3   = E
 
4  4   4   4   = N

Then

 5  5   5   5   =  ?

Crack This Logic!



Skip To The Answer!

Cracked 'THAT' Logic!


Or look at the question first!


 Let's have a look at the given equations once again.

1   1   1   1    =  R
 
2  2   2   2   =  T

3  3   3   3   = E

4  4   4   4   = N

If rewritten after adding numbers & addition is spelled then,

1   1   1   1    =  FOUR
    
2  2   2   2   =  EIGHT

3  3   3   3   = THREE

 4  4   4   4   = SIXTEEN

 Clearly, last letter of spelling is taken.

Hence,


5  5  5  5 = TWENTY

5  5  5  5 = Y  

Cracked 'THAT' Logic!

Correct The Incorrect

Just move 1 match stick to correct the equation.


Correct The Incorrect

 





Find here how to correct it!

Correcting The Incorrect


What was the wrong?

All we need to do is move 'this' pointed match stick.


Correcting The Incorrect

Now it looks like - 

Correcting The Incorrect

This is now correct equation. Isn't it?

Special Squence Of Numbers

What is special about the following sequence of numbers?

8 5 4 9 1 7 6 10 3 2 0

Special Squence Of Numbers


This is how it's special!

Speciality of Special Sequence


Here is that sequence!

Looking at the special sequence once again.

8 5 4 9 1 7 6 10 3 2 0

If they are spelled as in sequence -

Eight   Five   Four   Nine   One   Seven   Six   Ten   Three   Two   Zero 

Yes, you got it right. They are in an alphabetical order.


Speciality of Special Sequence

The Hiker's Dilemma

A hiker comes across an intersection where three roads cross. He looks for the sign indicating the direction to his destination city. He finds that the pole carrying three city names and arrows pointing to them has fallen. He picks it up, considers it, and pops it back into place, pointing out the correct direction for his destination. How did he do it?

The Hiker's Dilemma


This is how he did it!


Hiker Got The Right Direction


What was the dilemma? 

Since he knew very well from which city he came; he just oriented that arrow in right direction. And obviously hence rest of all arrows are pointed in the right directions as well. This is how he found his right way!

Hiker Got The Right Direction

A Fractional Pink Shade

What fraction of this figure is shaded with the pink color?

Find Area Of A Fractional Pink Shade

Get the answer here!


Author : Ed Southall of Solve My Maths

Area Of A Fractional Pink Shade


A look at the question first!

Let's first recall the formula for the calculation of area of a triangle.

Area of triangle =  1/2 x Base x Height

Let's assume the side of the square is 1.

Now the triangle with the pink shade & triangle opposite to it are similar triangles. Similar triangles are triangle whose sides are in proportion with each other.

Since here base of pink triangle is double of un shaded opposite triangle, the height of pink triangle must be double of that smaller triangle.

But together, heights of both triangles must be equal to side of the square i.e. 1.

And hence, height of smaller triangle must be 1/3 & that of pink 2/3. (h + 2h = 3 ; h = 1/3).

So,

Area of Pink Triangle = 1/2 x Base x Height = 1/2 x 1 x 2/3 = 1/3.

So the area of pink shaded part is 1/3rd of total area occupied by square.



 

Tricky Logical Mathematical Puzzle

Answer of Tricky Logical Mathematical Puzzle


Or a look at the question itself?


Let's look at the puzzle once again.


Answer of Tricky Logical Mathematical Puzzle


From first equation, it is clear that figure = 15. But the figure itself made up of square (4 sides) + polygon (5 sides) + hexagon (6 sides) = 15.

From second equation, we have bunch of 4 bananas = 4 i.e. 1 banana = 1.

And from third equation, we have 3 hours in clock = 3 i.e. 1 hours  = 1.

Hence, in fourth equation, value of clock = 2, 3 bananas = 3, figure = sides of hexagon + sides of pentagons = 6 + 5 = 11.

2 + 3 + 3 x 11 = 38

Hence, answer is 38

Wish Of Cigarette Smoking

Bruce is an inmate at a large prison, and like most of the other prisoners, he smokes cigarettes. During his time in the prison, Bruce finds that if he has 3 cigarette butts, he can cram them together and turn them into 1 full cigarette. Whenever he smokes a cigarette, it turns into a cigarette butt.

One day, Bruce is in his cell talking to one of his cellmates, Steve.

“I really want to smoke 5 cigarettes today, but all I have are these 10 cigarette butts,” Bruce tells Steve. “I’m not sure that will be enough.”

“Why don’t you borrow some of Tom’s cigarette butts?” asks Steve, pointing over to a small pile of cigarette butts on the bed of their third cellmate, Tom, who is out for the day on a community service project.

“I can’t,” Bruce says. “Tom always counts exactly how many cigarette butts are in his pile, and he’d probably kill me if he noticed that I had taken any.”

However, after thinking for a while, Bruce figures out a way that he can smoke 5 cigarettes without angering Tom. What is his plan?



Wish Of 5 Cigarettes Smoking - Logical Puzzles

That's his master plan!

Fulfilling The Wish Of Cigarette Smoking


What was the challenge? 

Bruce takes 9 of his 10 cigarette butts and make 3 cigarettes using those 9 (9/3=3). Now, he smokes all 3 cigarettes. At this point, he has 3 + 1 = 4 cigarette butts.

Using 3 out of 4 cigarette butts, he make one another cigarette and smokes it. Now he has 1 + 1 = 2 cigarette butts & till now has smoked 4 cigarettes.

Now he borrows 1 Tom's cigarette butts making total number of cigarette butts equal to 3. Using these 3 butts he makes one more cigarette and this way he smokes 5th cigarette. 


After smoking this 5th, he puts back the cigarette butt left in Tom's pile so that Tom won't find anything missing.

Plan For Fulfilling The Wish Of Cigarette Smoking - Logical Puzzles

Which way is the bus going? Left or Right?

Can you guess in which direction this bus is going?



 Left or Right? Which way is the bus going?


Are you in the right direction?

Bus is Moving In 'This' Direction!


Why dirction was asked to find? 


Well, it totally depends on the location of the bus. How? Read further.

If you look at it carefully, then you can notice that the doors of the bus are missing.
That clearly indicates, those must be on the other side of bus.

Hence if bus is on the roads of India then it must have doors at it's left side & hence the bus must be moving in the right direction.

Bus is Moving In 'RIGHT' Direction!


While in some countries, bus might have doors at the right; in the case the bus must be moving in left direction. 


Bus is Moving In 'LEFT' Direction!

Viral Maths Problem Confusing Students & Parents

There are 73 red, blue and green marbles in a jar. There are twice as many red marbles as blue marbles. There are 19 more marbles than green marbles. 

Viral Maths Problem Confusing Students & Parents


How many green marbles are there?

Check if you are correct! 


Solution of Viral Maths Problem Confusing Students & Parents


What was the problem?


Solution of Viral Maths Problem Confusing Students & Parents



Using Algebra : 

Let r,b and g be the numbers of red, blue and green marbles in the jar.

There are 73 red, blue and green marbles in a jar.

So r + b + g = 73    .....(1)

There are twice as many red marbles as blue marbles.

r = 2b                  ......(2)

There are 19 more blue marbles than green marbles. 

b = g + 19            


g = b - 19            ......(3)

Putting (2) and (3) in (1), gives

2b + b + b - 19 = 73

4b = 92

b = 23

Putting b = 23 in (3) gives,

g = 23 - 19 = 4

Putting  b = 23 in (2), gives 

r = 2x23 = 46

So there are 46 red,23 blue and 4 green marbles in the jar.

Without Algebra :

In the case, we need to try trail and error method.

If g = 1, then b = 20 and r = 2(20) = 40 giving total 40 + 20 + 1 = 61.

If g = 2, then b = 21 and r = 2(21) = 42 giving total 42 + 21 + 2 = 65.

If g = 3, then b = 22 and r = 2(22) = 44 giving total 44 + 22 + 3 = 69.

Total is increasing at the rate of 4. So finally,

If g = 4, then b = 23 and r = 2(23) = 46 giving total 46 + 23 + 4 = 73.


So there are 46 red,23 blue and 4 green marbles in the jar.

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