The 100 Seat Airplane
People are waiting in line to board a 100-seat airplane. Steve is the first person in the line. He gets on the plane but suddenly can't remember what his seat number is, so he picks a seat at random. After that, each person who gets on the plane sits in their assigned seat if it's available, otherwise they will choose an open seat at random to sit in.
The flight is full and you are last in line. What is the probability that you get to sit in your assigned seat?
The flight is full and you are last in line. What is the probability that you get to sit in your assigned seat?
Hint: You don't need to use complex math to solve this riddle. Consider these two questions:
What happens if somebody sits in your seat?
What happens if somebody sits in Steve's assigned seat?
The correct answer is 1/2.
The chase that the first person in line takes your seat is equal to the chance that he takes his own seat. If he takes his own seat initially then you have a 100% chance of sitting in your seat, if he takes your seat you have a 0 percent chance. Now after the first person has picked a seat, the second person will enter the plan and, if the first person has sat in his seat, he will pick randomly, and again, the chance that he picks your seat is equal to the chance he picks someone your seat. The motion will continue until someone sits in the first persons seat, at this point the remaining people standing in line which each be able to sit in their own seats. Well how does that probability look in equation form? (2/100) * 50% + (98/100) * ( (2/98) * 50% + (96/98) * ( (2/96) * (50%) +... (2/2) * (50%) ) ) This expansion reduces to 1/2.
An easy way to see this is trying the problem with a 3 or 4 person scenario (pretend its a car). Both scenarios have probabilities of 1/2. Did you answer this riddle correctly?
YES NO
The chase that the first person in line takes your seat is equal to the chance that he takes his own seat. If he takes his own seat initially then you have a 100% chance of sitting in your seat, if he takes your seat you have a 0 percent chance. Now after the first person has picked a seat, the second person will enter the plan and, if the first person has sat in his seat, he will pick randomly, and again, the chance that he picks your seat is equal to the chance he picks someone your seat. The motion will continue until someone sits in the first persons seat, at this point the remaining people standing in line which each be able to sit in their own seats. Well how does that probability look in equation form? (2/100) * 50% + (98/100) * ( (2/98) * 50% + (96/98) * ( (2/96) * (50%) +... (2/2) * (50%) ) ) This expansion reduces to 1/2.
An easy way to see this is trying the problem with a 3 or 4 person scenario (pretend its a car). Both scenarios have probabilities of 1/2. Did you answer this riddle correctly?
YES NO
A Farmer Crossing A River
A farmer has to get a sack of corn, a chicken, and a fox across a river. The farmer is only able to bring one of the above items along with him at a time. The only problem is if he leaves the fox alone with the chicken, the fox will eat the chicken, and if he leaves the chicken along the corn sack, then the chicken will eat the corn sack. How does the farmer get all 3 items across safely?
Hint: The farmer can bring items across the river both ways.The farmer brings the chicken across the river first.
The farmer brings the chicken across. Goes back and brings the fox across, and brings the chicken back with him to the other side of the river and drops off the chicken, then he goes and brings the corn sack across, and finally he goes back for the chicken and brings it across. Did you answer this riddle correctly?
YES NO
YES NO
The Dog Or Your Wife Riddle
If your dog is barking at the back door and your wife is yelling at the front door, whom do you let in first?
Hint:
The Longest Camping Trip Riddle
A group of campers have been on vacation so long, that they've forgotten the day of the week. The following conversation ensues.
Darryl: What's the day? I dont think it is Thursday, Friday or Saturday.
Tracy: Well that doesn't narrow it down much. Yesterday was Sunday.
Melissa: Yesterday wasn't Sunday, tomorrow is Sunday.
Ben: The day after tomorrow is Saturday.
Adrienne: The day before yesterday was Thursday.
Susie: Tomorrow is Saturday.
David: I know that the day after tomorrow is not Friday.
If only one person's statement is true, what day of the week is it?
Darryl: What's the day? I dont think it is Thursday, Friday or Saturday.
Tracy: Well that doesn't narrow it down much. Yesterday was Sunday.
Melissa: Yesterday wasn't Sunday, tomorrow is Sunday.
Ben: The day after tomorrow is Saturday.
Adrienne: The day before yesterday was Thursday.
Susie: Tomorrow is Saturday.
David: I know that the day after tomorrow is not Friday.
If only one person's statement is true, what day of the week is it?
Hint:
It is Wednesday. If it was any other day of the week, more than one statement would be true. To solve the riddle, evaluate each person's statement and write down what day it could be according to the statement. David's statement indicates it could be any day of the week except for Wednesday. When you list the days that it could be according to everyone's statement, it turns out Wednesday is the day mentioned only one time. Darryl: Sunday, Monday, Tuesday, or Wednesday Tracy: Monday Melissa: Saturday Ben: Thursday Adrienne: Saturday Susie: Friday David: Sunday, Monday, Tuesday, Thursday, Friday or Saturday Did you answer this riddle correctly?
YES NO
YES NO
Sam And Angela's Camping Trip
Hint:
Angela first lit one mosquito coil at both ends and then lit the other on only one side. The coil which had been lit on both ends finished burning in one-half hour. At that point the second mosquito coil had one-half hour left to burn. Angela lit the second coil at the other end, and it finished burning fifteen minutes later. (45 minutes total) Did you answer this riddle correctly?
YES NO
YES NO
Marrying The Princess Riddle
A king wants his daughter to marry the smartest of 3 extremely intelligent young princes, and so the king's wise men devised an intelligence test.
The princes are gathered into a room and seated, facing one another, and are shown 2 black hats and 3 white hats. They are blindfolded, and 1 hat is placed on each of their heads, with the remaining hats hidden in a different room.
The king tells them that the first prince to deduce the color of his hat without removing it or looking at it will marry his daughter. A wrong guess will mean death. The blindfolds are then removed.
You are one of the princes. You see 2 white hats on the other prince's heads. After some time you realize that the other prince's are unable to deduce the color of their hat, or are unwilling to guess. What color is your hat?
The princes are gathered into a room and seated, facing one another, and are shown 2 black hats and 3 white hats. They are blindfolded, and 1 hat is placed on each of their heads, with the remaining hats hidden in a different room.
The king tells them that the first prince to deduce the color of his hat without removing it or looking at it will marry his daughter. A wrong guess will mean death. The blindfolds are then removed.
You are one of the princes. You see 2 white hats on the other prince's heads. After some time you realize that the other prince's are unable to deduce the color of their hat, or are unwilling to guess. What color is your hat?
Hint: You know that your competitors are very intelligent and want nothing more than to marry the princess. You also know that the king is a man of his word, and he has said that the test is a fair test of intelligence and bravery.
Answer: White.
The king would not select two white hats and one black hat. This would mean two princes would see one black hat and one white hat. You would be at a disadvantage if you were the only prince wearing a black hat.
If you were wearing the black hat, it would not take long for one of the other princes to deduce he was wearing a white hat.
If an intelligent prince saw a white hat and a black hat, he would eventually realize that the king would never select two black hats and one white hat. Any prince seeing two black hats would instantly know he was wearing a white hat. Therefore if a prince can see one black hat, he can work out he is wearing white.
Therefore the only fair test is for all three princes to be wearing white hats. After waiting some time just to be sure, you can safely assert you are wearing a white hat. Did you answer this riddle correctly?
YES NO
The king would not select two white hats and one black hat. This would mean two princes would see one black hat and one white hat. You would be at a disadvantage if you were the only prince wearing a black hat.
If you were wearing the black hat, it would not take long for one of the other princes to deduce he was wearing a white hat.
If an intelligent prince saw a white hat and a black hat, he would eventually realize that the king would never select two black hats and one white hat. Any prince seeing two black hats would instantly know he was wearing a white hat. Therefore if a prince can see one black hat, he can work out he is wearing white.
Therefore the only fair test is for all three princes to be wearing white hats. After waiting some time just to be sure, you can safely assert you are wearing a white hat. 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
The Farmer In Australia
A farmer in Australia grows a beautiful pear tree, which he harvests to supply fruit to all the nearby grocery stores.
One of the store owners has called the farmer to see how much fruit is available that he can buy. Unfortunately the farmer isn't currently near the tree, so he has to work it out in his head.
He knows that the main trunk of the tree has 24 branches. That each branch has 12 boughs and that each bough has only got 6 twigs. Each one of these twigs bears one piece of fruit, so how many plums will he be able to sell to the store owner?
One of the store owners has called the farmer to see how much fruit is available that he can buy. Unfortunately the farmer isn't currently near the tree, so he has to work it out in his head.
He knows that the main trunk of the tree has 24 branches. That each branch has 12 boughs and that each bough has only got 6 twigs. Each one of these twigs bears one piece of fruit, so how many plums will he be able to sell to the store owner?
Hint:
None! He doesn't own a PLUM tree... he owns a PEAR trear! Did you answer this riddle correctly?
YES NO
YES NO
Doorway To Heaven
You die then you find yourself in limbo, and you see two doors. One of them leads you to hell and the other one heaven. They are being guarded by two guardians. The guardian guarding the doorway to heaven always tells the truth and the guardian guarding the doorway to hell always lies. What is the one question you will ask to either of the guardians to find out which door will lead you to heaven?
Hint:
If I asked the other guardian which door leads to heaven, what would he tell me? Did you answer this riddle correctly?
YES NO
YES NO
5 Houses Riddle
Here's more information:
An Englishman resides in a red house.
The Dane drinks tea.
Dogs are kept by the Swede.
The green house is left to the white house.
The occupant of the green house drinks coffee.
The birds are kept by the Pall Mall smoker.
The horse keeper and the Dunhill smoker live next to each other.
The German smokes Prince.
The Norwegian lives right next to the blue house.
The blend smoker's neighbor drinks water.
Hint:
3 Gods Riddle
Hint:
Question 1: (To any of the three gods) If I were to ask you "Is that the random god," would your answer be "ja?" (This questions, no matter the answer, will enable you to tell which god is not random i.e. the god who is either False or True)
Question 2: (To either the True or False god) If I asked you "are you false," would your answer be "ja?"
Question 3: (To the same god you asked the second question) If I asked you "whether the first god I spoke to is random," would your answer be "ja?" Did you answer this riddle correctly?
YES NO
Question 2: (To either the True or False god) If I asked you "are you false," would your answer be "ja?"
Question 3: (To the same god you asked the second question) If I asked you "whether the first god I spoke to is random," would your answer be "ja?" Did you answer this riddle correctly?
YES NO
The 2 Barbershops
There is a small town on the East Coast that has 2 barbershops each with a single barber, and on opposite sides of town. The barbershop in the good part of town is immaculate. The floors and windows are washed and the air is fresh. The barber is very friendly, always smiling, he has shined shoes, a nice head of hair, and a clean dress shirt. The barbershop in the bad part of town is a mess. The entire barbershop is covered with a layer of dirt, and the air smells of trash. The barber always has a frown on his face. His skin is oily, his hair is ragged, and there are always stains visible on his shirt.
A man comes into town and hears of both barbershops and the man decides to go to the dirty barbershop in the bad part of town. Why does he do this?
A man comes into town and hears of both barbershops and the man decides to go to the dirty barbershop in the bad part of town. Why does he do this?
Hint:
The clean-cut barber must have his hair cut by the dirty barber and the dirty barber by the clean-cut barber. So its obvious that the dirty barber gives a better haircut. Did you answer this riddle correctly?
YES NO
YES NO
A Boy At The Carnival
A young boy was at the carnival. He was walking past a kiosk where an old man was sitting.
"Do you want to play a game?" the old man said to him.The young boy was intrigued. "What kind of game?" he asked.
"It's a very simple game." said the old man. "I will tell you the rules. I have ten large metal boxes. Inside one of the boxes is the prize money. One thousand dollars."
"A thousand bucks, huh?" asked the boy. "What's the catch?"
"The boxes are sturdy and strong," said the old man. "Much too strong to be opened with your bare hands. They are also airtight and cannot be damaged by a hammer, an axe or even a chainsaw."
"So they're impossible to open?" said the boy.
"Not impossible." said the man. "I have a blowtorch which can be used to open the boxes."
"Is there a time limit?" asked the boy.
"You can take as much time as you want." said the old man. "When you find the prize money, it's all yours. So, do you want to play the game?"
"Well, I don't how I could possibly lose," said the boy. "OK. I'll play your game."
The old man smiled. "I'll make it very easy for you", he said. "There are ten metal boxes, but if you give me five dollars, I will start you right next to the prize money."
The boy happily took out his wallet and handed a crisp five dollar note to the old man. There was a mischievous grin on the old man's face.The game started.The prize money was right in front of the boy. He could see it. He could touch it.Even though he won the game, the boy was never able to spend the money. He died shortly after he won the game.
How did the boy die?
"Do you want to play a game?" the old man said to him.The young boy was intrigued. "What kind of game?" he asked.
"It's a very simple game." said the old man. "I will tell you the rules. I have ten large metal boxes. Inside one of the boxes is the prize money. One thousand dollars."
"A thousand bucks, huh?" asked the boy. "What's the catch?"
"The boxes are sturdy and strong," said the old man. "Much too strong to be opened with your bare hands. They are also airtight and cannot be damaged by a hammer, an axe or even a chainsaw."
"So they're impossible to open?" said the boy.
"Not impossible." said the man. "I have a blowtorch which can be used to open the boxes."
"Is there a time limit?" asked the boy.
"You can take as much time as you want." said the old man. "When you find the prize money, it's all yours. So, do you want to play the game?"
"Well, I don't how I could possibly lose," said the boy. "OK. I'll play your game."
The old man smiled. "I'll make it very easy for you", he said. "There are ten metal boxes, but if you give me five dollars, I will start you right next to the prize money."
The boy happily took out his wallet and handed a crisp five dollar note to the old man. There was a mischievous grin on the old man's face.The game started.The prize money was right in front of the boy. He could see it. He could touch it.Even though he won the game, the boy was never able to spend the money. He died shortly after he won the game.
How did the boy die?
Hint:
The man put the inside of the box since he said for five dollars, he'd put the boy next to the money. Since the box was airtight, he suffocated Did you answer this riddle correctly?
YES NO
YES NO
Panning Gold Riddle
Before dying, a father left a will to his two sons telling of a gold-panning stream that had supported his father's family long and hard. The will said that the two sons could make one, only one trip to the stream to pan for gold, but for as long as they wanted, and that whoever carried the gold back got it. On their way to the stream, the two sons lost a big fraction of their supplies, reducing their stay to two months. All they had now were some food, a mule, and panning supplies. During their stay, they managed to pan and smelt a gold bar 5 inches in diameter and 5 inches in height. Back in their hometown, the two sons disputed long and hard in court over who should get the gold bar. Now, the judge was a wise one. Who did he say got the gold bar?
Hint:
The mule. A gold bar 5 inches in diameter and 5 inches in height would have weighed far too much for either of the sons to carry, only the mule could have. Did you answer this riddle correctly?
YES NO
YES NO
The Multistory Building Suicide Riddle
A homicide detective is called upon a crime scene. He finds that a body is lying on the ground in front of a multistory building. By all the means, it looks like a simple suicide case. But there are doubts in his mind.
He goes to the first floor and moves into the room facing the direction of the body. He opens the window in that direction and looks down towards his team. The he goes to the second floor and again moves into the room facing that direction, opens the window and looks down at his team.
He continues with the same process till the top floor. After that, he returns back to where his team is standing. He tells them that it is a suicide.
How did he come to such a conclusion?
He goes to the first floor and moves into the room facing the direction of the body. He opens the window in that direction and looks down towards his team. The he goes to the second floor and again moves into the room facing that direction, opens the window and looks down at his team.
He continues with the same process till the top floor. After that, he returns back to where his team is standing. He tells them that it is a suicide.
How did he come to such a conclusion?
Hint:
At every floor, the detective had to open the window himself. If the man had committed suicide, then at least one of the windows must have been open. A person who is committing suicide wont close the window behind him. Thus he knows that someone pushed him off the edge and closed the window afterwards. Did you answer this riddle correctly?
YES NO
YES NO
Add Your Riddle Here
Have some tricky riddles of your own? Leave them below for our users to try and solve.