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Nine brilliant most students were summoned by an inspecting professor. He gave them a situation and told them that he is having nine hats. The hats are either red colored or blue colored as told by the professor. He also tells them that he have at least one red colored hat and the number of blue hats are greater than the red hats.

He places one hat on each of their heads. The students are not allowed to talk with each other and no means of communication is feasible. He asks them how many hats are blue and how many are red. He gives them half an hour to deduce and moves out of the room. Nobody is able to answer when he returns back and thus he gives them another fifteen minutes. But when he returns, no one can answer again. Thus he gives them final five minutes. On returning back this time, everyone was available with an accurate answer.

How could the students have deduced the right answer? What is the right answer?

He places one hat on each of their heads. The students are not allowed to talk with each other and no means of communication is feasible. He asks them how many hats are blue and how many are red. He gives them half an hour to deduce and moves out of the room. Nobody is able to answer when he returns back and thus he gives them another fifteen minutes. But when he returns, no one can answer again. Thus he gives them final five minutes. On returning back this time, everyone was available with an accurate answer.

How could the students have deduced the right answer? What is the right answer?

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You are given a set of scales and 12 marbles. The scales are of the old balance variety. That is, a small dish hangs from each end of a rod that is balanced in the middle. The device enables you to conclude either that the contents of the dishes weigh the same or that the dish that falls lower has heavier contents than the other.

The 12 marbles appear to be identical. In fact, 11 of them are identical, and one is of a different weight. Your task is to identify the unusual marble and discard it. You are allowed to use the scales three times if you wish, but no more.

Note that the unusual marble may be heavier or lighter than the others. You are asked to both identify it and determine whether it is heavy or light.
**category** :
LOGIC

The 12 marbles appear to be identical. In fact, 11 of them are identical, and one is of a different weight. Your task is to identify the unusual marble and discard it. You are allowed to use the scales three times if you wish, but no more.

Note that the unusual marble may be heavier or lighter than the others. You are asked to both identify it and determine whether it is heavy or light.

Difficulty Popularity

I have two rectangular bars.

They have property such that when you light the fire from one end , it will take exactly 60 seconds to get completely burn.

However they do not burn at consistent speed (i.e it might be possible that 40 percent burn in 55 seconds and next 60 percent can burn in 10 seconds).

Problem is : How do you measure 45 seconds ?

They have property such that when you light the fire from one end , it will take exactly 60 seconds to get completely burn.

However they do not burn at consistent speed (i.e it might be possible that 40 percent burn in 55 seconds and next 60 percent can burn in 10 seconds).

Problem is : How do you measure 45 seconds ?

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Let us say that a table tennis tournament was going on with knock out terms which means the one who loses the match is out of the tournament. 100 players took part in that tournament.

How many matches were played?

How many matches were played?

Difficulty Popularity

This one is a bit of tricky river crossing puzzle than you might have solved till now. We have a whole family out on a picnic on one side of the river. The family includes Mother and Father, two sons, two daughters, a maid and a dog. The bridge broke down and all they have is a boat that can take them towards the other side of the river. But there is a condition with the boat. It can hold just two persons at one time (count the dog as one person).

No it does not limit to that and there are other complications. The dog can’t be left without the maid or it will bite the family members. The father can’t be left with daughters without the mother and in the same manner, the mother can’t be left alone with the sons without the father. Also an adult is needed to drive the boat and it can’t drive by itself.

How will all of them reach the other side of the river?

No it does not limit to that and there are other complications. The dog can’t be left without the maid or it will bite the family members. The father can’t be left with daughters without the mother and in the same manner, the mother can’t be left alone with the sons without the father. Also an adult is needed to drive the boat and it can’t drive by itself.

How will all of them reach the other side of the river?

Difficulty Popularity

In a recreational activity, you are given four different jars of 2 liters, 4 liters, 6 liters and 8 liters respectively with an unlimited water supply. Then you are asked to measure exactly 5 liters of water using them.

How will you do it?

How will you do it?

Difficulty Popularity

You can place weights on both side of weighing balance and you need to measure all weights between 1 and 1000. For example if you have weights 1 and 3,now you can measure 1,3 and 4 like earlier case, and also you can measure 2,by placing 3 on one side and 1 on the side which contain the substance to be weighed. So question again is how many minimum weights and of what denominations you need to measure all weights from 1kg to 1000kg.

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A barman is having a 12 liters jug full of beer. He needs to divide or split that beer into two equal parts. All he has is two empty jugs of capacity 8 liters and 5 liters.

How will he do it using them?

How will he do it using them?

Difficulty Popularity

I can prove why 1 = 2

Step1. Lets say y = x

Step2. Multiply through by x xy = x2

Step3. Subtract y2 from each side xy - y2 = x2 - y2

Step4. Factor each side y(x-y) = (x+y)(x-y)

Step5. Divide both sides by (x-y) y = x+y

Step6. Divide both sides by y y/y = x/y + y/y

Step7. And so... 1 = x/y + 1

Step8. Since x=y, x/y = 1 1 = 1 + 1

Step9. And so... 1 = 2

How is this possible ?

Step1. Lets say y = x

Step2. Multiply through by x xy = x2

Step3. Subtract y2 from each side xy - y2 = x2 - y2

Step4. Factor each side y(x-y) = (x+y)(x-y)

Step5. Divide both sides by (x-y) y = x+y

Step6. Divide both sides by y y/y = x/y + y/y

Step7. And so... 1 = x/y + 1

Step8. Since x=y, x/y = 1 1 = 1 + 1

Step9. And so... 1 = 2

How is this possible ?

Difficulty Popularity

There are three bags.The first bag has two blue rocks. The second bag has two red rocks. The third bag has a blue and a red rock. All bags are labeled but all labels are wrong.You are allowed to open one bag, pick one rock at random, see its color and put it back into the bag, without seeing the color of the other rock.

How many such operations are necessary to correctly label the bags ?

How many such operations are necessary to correctly label the bags ?

Difficulty Popularity

A great meeting is held by a great logician where all the other logicians are called upon. The master logician takes them in a room and makes them sit in circle. A hat is placed on each of their heads. Now all of them can see the color of hats others are wearing but can’t see his own. They are told that there different colors of hats.

The master logician explains that a bell will be rung at regular intervals and the moment when a logician knows the color of his hat, he will leave on the next bell. If anyone leaves at the wrong bell, he will be disqualified and sent home.

All of them are assured of one thing that the puzzle will not be impossible for anyone of them. How will they manage the situation?
**category** :
LOGIC

The master logician explains that a bell will be rung at regular intervals and the moment when a logician knows the color of his hat, he will leave on the next bell. If anyone leaves at the wrong bell, he will be disqualified and sent home.

All of them are assured of one thing that the puzzle will not be impossible for anyone of them. How will they manage the situation?

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