Three Rivers Riddle
There are three rivers and after each river lies a grave. A man wants to leave the same number of flowers at each grave and be left with none at the end. However, each time he passes through a river, the number of flowers he has doubles. How many flowers does he have to start with so that he is left with none at the end? And how many does he leave at each grave?
Hint:
This problem has an infinite number of solutions modeled by the equation 8a=7n, where a is the amount of flowers the man starts with and n is the number of flowers he leaves at each grave. The simplest and possibly trivial solution would be to start with 0 flowers and leave 0 flowers at each grave. A more significant solution would be to start with 7 flowers and leave 8 at each grave. Any positive integer multiple of this solution also satisfies the conditions. For example, the man starts with 14 flowers and leaves 16 at each grave; so, 14 doubles to 28, and 28-16= 12; 12 doubles to 24, and 24-16= 8; 8 doubles to 16, and 16-16= 0. The result is the same if the man starts with 21 flowers and leaves 24 flowers at each grave, or starts with 28 and leaves 32. Did you answer this riddle correctly?
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Flip The Switch Riddle
There is a prison with 100 prisoners, each in separate cells with no form of contact. There is an area in the prison with a single light bulb in it. Each day, the warden picks one of the prisoners at random, even if they have been picked before, and takes them out to the lobby. The prisoner will have the choice to flip the switch if they want. The light bulb starts off.
When a prisoner is taken into the area with the light bulb, he can also say "Every prisoner has been brought to the light bulb." If this is true all prisoners will go free. However, if a prisoner chooses to say this and it's wrong, all the prisoners will be executed. So a prisoner should only say this if he knows it is true for sure.
Before the first day of this process begins, all the prisoners are allowed to get together to discuss a strategy to eventually save themselves.
What strategy could they use to ensure they will go free?
When a prisoner is taken into the area with the light bulb, he can also say "Every prisoner has been brought to the light bulb." If this is true all prisoners will go free. However, if a prisoner chooses to say this and it's wrong, all the prisoners will be executed. So a prisoner should only say this if he knows it is true for sure.
Before the first day of this process begins, all the prisoners are allowed to get together to discuss a strategy to eventually save themselves.
What strategy could they use to ensure they will go free?
Hint:
Only allow one prisoner to turn the light bulb off and all of the others turn it on if they have never turned it on before. If they have turned it on before they do nothing. The prisoner that can turn it off then knows they have all been there and saves them all when he has turned it off 99 times. Did you answer this riddle correctly?
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YES NO
Burns Me There Riddle
Hint:
Rearrange the letters of BURN ME THERE and they spell out the words THREE NUMBERS! Did you answer this riddle correctly?
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YES NO
Killed Her Own Sister Riddle
A woman killed her own sister. During the interrogation, she told a story that she had just attended her own mother's funeral a few days before the crime took place. While at the funeral, she said that she met a guy whom she did not know. She thought this guy was amazing, so much her dream guy that she believed him to be just that! She fell in love with him right there, but never asked for his number and could not find him. A few days later, she killed her sister.
Although this woman has confessed to the crime, police are still intrigued by the story, especially because she won't tell them her motive. Hearing this tragic story, with his psychological education background, Detective Thompson easily guessed the woman's motive.
Why did the woman killed her own sister?
Although this woman has confessed to the crime, police are still intrigued by the story, especially because she won't tell them her motive. Hearing this tragic story, with his psychological education background, Detective Thompson easily guessed the woman's motive.
Why did the woman killed her own sister?
Hint:
She was hoping that the guy would appear at the funeral again. Did you answer this riddle correctly?
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YES NO
Construction Site Murder Riddle
A workman was killed at a construction site. The police began questioning a number of the other fellow workers. Based on past scrapes with the law, many of the following workers were considered prime suspects:
* The electrician was suspected of wiretapping once but was never charged.
* The carpenter thought he was a stud. He tried to frame another man one time.
* The glazier went to great panes to conceal his past. He still claims that he didnt do anything, that he was framed.
* The painter had a brush with the law several years ago.
* The heating, ventilation and air conditioning contractor was known to pack heat. He was arrested once but duct the charges.
* The mason was a prime suspect because he gets stoned regularly.
* The cabinet maker is an accomplished counter fitter.
The autopsy led the police to arrest the carpenter, who subsequently confessed. Why?
* The electrician was suspected of wiretapping once but was never charged.
* The carpenter thought he was a stud. He tried to frame another man one time.
* The glazier went to great panes to conceal his past. He still claims that he didnt do anything, that he was framed.
* The painter had a brush with the law several years ago.
* The heating, ventilation and air conditioning contractor was known to pack heat. He was arrested once but duct the charges.
* The mason was a prime suspect because he gets stoned regularly.
* The cabinet maker is an accomplished counter fitter.
The autopsy led the police to arrest the carpenter, who subsequently confessed. Why?
Hint:
The evidence against him was irrefutable. It was found that the workman, when he died, was hammered. Did you answer this riddle correctly?
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Adding Eights Riddle
Hint:
The Riddle Of Sphinx
Hint:
A person: ("Legs" is a metaphor for hands and knees in the first description and two legs and a cane in the last.) Did you answer this riddle correctly?
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YES NO
Coins In My Wallet Riddle
I have 100 coins in my wallet.
What is the minimum number of coin(s), I would be required in order to make sure each coin touched exactly three other coins.
What is the minimum number of coin(s), I would be required in order to make sure each coin touched exactly three other coins.
Hint:
4
3 placed flat on the table in a triangle(touching each other) and put the fourth one on top of them in the middle. Did you answer this riddle correctly?
YES NO
3 placed flat on the table in a triangle(touching each other) and put the fourth one on top of them in the middle. Did you answer this riddle correctly?
YES NO
Grapeland To Applecity
You have to send 3,000 grapes 1,000 kilometers from grapecity to appleland. Your truck can carry 1,000 grapes at a time. Every time you travel a kilometer towards appleland you must pay a tax of 1 grape but you pay nothing when going in the other direction (towards grapecity).
What is highest number of grapes you can get to appleland?
What is highest number of grapes you can get to appleland?
Hint:
Step one: First you want to make 3 trips of 1,000 grapes 333 kilometers. You will be left with 2,001 grapes and 667 kilometers to go.
Step two: Next you want to take 2 trips of 1,000 grapes 500 kilometers. You will be left with 1,000 grapes and 167 kilometers to go (you have to leave a grape behind).
Step three: Finally, you travel the last 167 kilometers with one load of 1,000 grapes and are left with 833 grapes in appleland. Did you answer this riddle correctly?
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Step two: Next you want to take 2 trips of 1,000 grapes 500 kilometers. You will be left with 1,000 grapes and 167 kilometers to go (you have to leave a grape behind).
Step three: Finally, you travel the last 167 kilometers with one load of 1,000 grapes and are left with 833 grapes in appleland. Did you answer this riddle correctly?
YES NO
A Pack Of 40 Cards
A pack of cards has 40 cards. You are blindfolded. Out of 40, 25 cards are facing down while 15 are facing up. You have been asked to divide this pack of cards into two decks - so that each deck contains an equal number of face up cards. Remember, you are blindfolded.
How will you do it?
How will you do it?
Hint:
Create a new deck of the exactly same number of cards as are face up cards in the original deck.Take 15 number of cards in a new deck and change their face direction. For example- You create a new deck of 15 cards and out of 15, 5 faces up in a new deck. So remaining 10 faces up are in the old deck. But hey! while creating the new deck you reversed the face direction of new cards. So actually the 5 cards which were facing up are actually face down in the new deck while 10 faces up. Did you answer this riddle correctly?
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Accepting The Bet Riddle
There is a box in which distinct numbered balls have been kept. You have to pick two balls randomly from the lot.
If someone is offering you a 2 to 1 odds that the numbers will be relatively prime, for example
If the balls you picked had the numbers 6 and 13, you lose $1.
If the balls you picked had the numbers 5 and 25, you win $2.
Will you accept that bet?
If someone is offering you a 2 to 1 odds that the numbers will be relatively prime, for example
If the balls you picked had the numbers 6 and 13, you lose $1.
If the balls you picked had the numbers 5 and 25, you win $2.
Will you accept that bet?
Hint:
Yes, you should accept the bet. Simply because the odds of picking two relatively prime numbers are 60%. It is a win-win situation for you if you keep playing. Did you answer this riddle correctly?
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A Special Integer Riddle
A special integer exists in mathematics that shows a special property. If you subtract any number from that integer, the result will always be divisible by the successor of that number completely.
Do you know what that integer is ?
Do you know what that integer is ?
Hint:
The required integer is -1.
For an example, let us subtract 7 from -1.
-1 - 7 = -8
Now the successor of 7 is 8 and (-8) is exactly divisible by 8.
You can try that for any number and it will hold true. Did you answer this riddle correctly?
YES NO
For an example, let us subtract 7 from -1.
-1 - 7 = -8
Now the successor of 7 is 8 and (-8) is exactly divisible by 8.
You can try that for any number and it will hold true. Did you answer this riddle correctly?
YES NO
21 Jars Riddle
You have 21 jars with you. Out of them, 7 are filled with water, 7 are half-full with water and 7 are empty. How will you distribute the jars among three people such that each one of them gets the equal number of jars and equal amount of water?
Hint:
Give 3 full, 1 half-full and 3 empty bottles to the first person.
Give 3 full, 1 half-full and 3 empty bottles to the second person.
Give 1 full, 5 half-full and 1 empty bottle to the third person. Did you answer this riddle correctly?
YES NO
Give 3 full, 1 half-full and 3 empty bottles to the second person.
Give 1 full, 5 half-full and 1 empty bottle to the third person. Did you answer this riddle correctly?
YES NO
Losing A New York Bet
You are hanging around in NYC when a person approaches you.
"Leaving the bald people aside, I can bet a hundred bucks that there are two people living in NYC who have same number of hairs on their heads," he says to you.
You say that you will take the bet. After talking to the man for a couple of minutes, you realize that you have lost the bet.
What did the person say to you that proved his statement ?
"Leaving the bald people aside, I can bet a hundred bucks that there are two people living in NYC who have same number of hairs on their heads," he says to you.
You say that you will take the bet. After talking to the man for a couple of minutes, you realize that you have lost the bet.
What did the person say to you that proved his statement ?
Hint:
This problem can be best solved using the pigeonhole principle.
The argument will go like this:
Assume that all the non-bald people in NYC have different number of hairs on their head. The population is about 9 million and let us assume that there are 8 million among them who are not bald.
Now, those 8 million people need to have different number of hairs. On an average, people have just 100, 000 hairs on their head. If we keep on assuming that there is someone with just one hair, someone with two, someone with three and so on, there will be 7, 900, 00 other people left who will have more than 100, 000 hairs on their head and need different number of hairs.
Now, as per this assumption, if we keep increasing one hair for each person, to make everybody hair different in numbers, we will come across someone with 8, 000, 000 hairs. But that is practically impossible (even 1, 000, 000 is impossible). Thus there must be two people who are having same number of hairs. Did you answer this riddle correctly?
YES NO
The argument will go like this:
Assume that all the non-bald people in NYC have different number of hairs on their head. The population is about 9 million and let us assume that there are 8 million among them who are not bald.
Now, those 8 million people need to have different number of hairs. On an average, people have just 100, 000 hairs on their head. If we keep on assuming that there is someone with just one hair, someone with two, someone with three and so on, there will be 7, 900, 00 other people left who will have more than 100, 000 hairs on their head and need different number of hairs.
Now, as per this assumption, if we keep increasing one hair for each person, to make everybody hair different in numbers, we will come across someone with 8, 000, 000 hairs. But that is practically impossible (even 1, 000, 000 is impossible). Thus there must be two people who are having same number of hairs. Did you answer this riddle correctly?
YES NO
Malcolm's Age Riddle
Malcolm is the number of weeks of his fathers age treated as days and his grandfathers age in months. All three of their ages add up to 120 years. How old is Malcolm, his father and his grandfather?
Hint:
Malcolm is 6.
The father is 42. 42 days = 6 weeks.
The grandfather is 72. 72 months = 6 years. Did you answer this riddle correctly?
YES NO
The father is 42. 42 days = 6 weeks.
The grandfather is 72. 72 months = 6 years. Did you answer this riddle correctly?
YES NO
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