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
Almost Hit By A Car Riddle
A man walked home after having been out drinking. He walked down the middle of a deserted country road. There were no streetlights to illuminate the road and there was no moonlight. He was dressed all in black. Suddenly a car that did not have its headlights on came racing down the road. At the last moment, the driver of the car saw the man and swerved to avoid him.
How did he manage to see him?
How did he manage to see him?
Hint:
He was returning home in the middle of the day, so anyone could have seen him. Did you answer this riddle correctly?
YES NO
YES NO
Breakfast And Tea Riddle
People can sell me, yet I have many clones.
I can bring you laughter between breakfast and tea,
Yet I can also break your heart easily.
I cover the earth like trees of old,
Whose leaves can blind and yet enfold.
Hint:
A book. Authors can speak to you through a book, yet the book makes no sound. Books are sold and have many duplicate copies. A book can bring the reader to tears and laughter, they span the globe and the leaves of a book (a single sheet in a book is called a leaf) can get you wrapped up in the story that youre unaware of whats going on around you. Did you answer this riddle correctly?
YES NO
YES NO
The Burning Island
You are in the center of on an island that is a kilometer long and half a kilometer wide. The vegetation is very dry from a long drought. Suddenly it catches fire at one end of the island, and a strong wind is blowing it towards you, burning the whole width of the island. There's no beach, only steep cliffs, and the sea is full of sharks. What can you do?
Hint:
Set fire to the other half of the island then walk behind the fire on to the burnt ground Did you answer this riddle correctly?
YES NO
YES NO
Elevator Accident Riddle
Im in an elevator with two other people. When it reaches the first floor, one person gets out and six get in. When it reaches the second floor, three people get out and twelve get in. At the third floor, five leave and nine enter. It rises to the fourth floor, one person gets on and the doors close. Suddenly, the elevator cable snaps and the car smashes to the ground. No one survives the fall, yet Im alive and know exactly how many people go on and off the elevator at every floor. How is this possible?
Hint:
I got off at the first floor. Im a security guard and knew how many people got on and off the elevator by watching the surveillance footage. Did you answer this riddle correctly?
YES NO
YES NO
A Man Steals 1000 From A Shop Riddle
Hint:
We can easily solve this mathematical problem by using the following mathematical process.
Initial loss amount = Rs. 1000
Now, we have to calculate the recovered amount,
As the man spends Rs. 700 in the shop, the shop owner will surely provide the man goods/services of Rs. 700. So, nothing will be recovered in this case.
Now, the man gave Rs. 1000 against the goods/services of Rs. 700 and got Rs. 300 change, so there will be no recovering of money for the shopkeeper.
Final loss = Initial loss - Recovered amount = 1000-0 = Rs. 1000 Did you answer this riddle correctly?
YES NO
Initial loss amount = Rs. 1000
Now, we have to calculate the recovered amount,
As the man spends Rs. 700 in the shop, the shop owner will surely provide the man goods/services of Rs. 700. So, nothing will be recovered in this case.
Now, the man gave Rs. 1000 against the goods/services of Rs. 700 and got Rs. 300 change, so there will be no recovering of money for the shopkeeper.
Final loss = Initial loss - Recovered amount = 1000-0 = Rs. 1000 Did you answer this riddle correctly?
YES NO
What Gets Wetter And Wetter The More It Dries Riddle
Hint: We use it everyday.
Billions Of Eyes
Hint:
Fighting For Hours
Hint: They live on a board. You are their lord.
Weep Beside Me
Hint:
What Color Is The Bear?
A man builds a house rectangular in shape. All the sides have southern exposure. A big bear walks by. What color is the bear? Why?
Hint:
The bear is white since the house is built on the North Pole. Did you answer this riddle correctly?
YES NO
YES NO
Paul's Weight
Paul's height is six feet, he's an assistant at a butcher's shop, and wears size 9 shoes. What does he weigh?
Hint:
The Red Hat
Once upon a time there lived a king who wished to find the wisest man in the realm to be his assistant. He summons the 3 known wisest men to his court and he administers the following test.
He sits them in a circle, facing each other and he says Im going to put either a red hat or a white hat on each of your heads. He proceeds to place a red hat on each of their heads. Obviously they can see each other but there are no mirrors in the room so they cant see whats on their heads. He says If you can see a red hat, raise your hand. They all raise their hands. Then he says If you can tell what color hat you have on, stand up.
Time goes on, one guy looks at another guy, he looks at the other guy. The other guy looks at him. Finally one guy stands up. The question is how did he know he was wearing a red hat?
He sits them in a circle, facing each other and he says Im going to put either a red hat or a white hat on each of your heads. He proceeds to place a red hat on each of their heads. Obviously they can see each other but there are no mirrors in the room so they cant see whats on their heads. He says If you can see a red hat, raise your hand. They all raise their hands. Then he says If you can tell what color hat you have on, stand up.
Time goes on, one guy looks at another guy, he looks at the other guy. The other guy looks at him. Finally one guy stands up. The question is how did he know he was wearing a red hat?
Hint: For a moment or two, nobody moved. Nobody knew for certain what color his hat was, and thats what told the wisest guy that all of the hats were red.
Step 1:
Wiseguy #1 knows he can see two red hats.
Step 2:
Wiseguy #1 thinks, "Hey, if I were wearing a white hat, Wiseguy #2 would see one red hat and one white."
Step 3:
Wiseguy #1 then thinks, "If I were wearing a white hat, and Wiseguy #2 saw one red hat and one white (and if he were wearing a white hat himself), then Wiseguy #3 would have seen two white hats. So, Wiseguy #3 wouldnt have raised his hand to the first question.
Wiseguy #1 thinks, "If that were true, Wiseguy #2 would be sure that he had a red hat. But since Wiseguy #2 was actually unsure about his hat color, it can only mean one thing, my hat is red." Did you answer this riddle correctly?
YES NO
Wiseguy #1 knows he can see two red hats.
Step 2:
Wiseguy #1 thinks, "Hey, if I were wearing a white hat, Wiseguy #2 would see one red hat and one white."
Step 3:
Wiseguy #1 then thinks, "If I were wearing a white hat, and Wiseguy #2 saw one red hat and one white (and if he were wearing a white hat himself), then Wiseguy #3 would have seen two white hats. So, Wiseguy #3 wouldnt have raised his hand to the first question.
Wiseguy #1 thinks, "If that were true, Wiseguy #2 would be sure that he had a red hat. But since Wiseguy #2 was actually unsure about his hat color, it can only mean one thing, my hat is red." Did you answer this riddle correctly?
YES NO
Eight Balls
There are eight balls, one of which is slightly heavier than the others. You have a two-armed scale, which you are allowed to use only twice. Find the ball thats heavier.
Hint:
Put three balls on each side of the scale. If the arms are equal, you know the heavy ball is one of the two remaining. If the arms are unequal, take the three balls on the heavier side, pick two and weigh them against each other. Did you answer this riddle correctly?
YES NO
YES NO
The Death Lift Riddle
A lift is on the ground floor. There are 4 people in the lift including me.
When the lift reaches 1st floor, 1 person gets out 3 people get in.
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 dies in the lift. How did I survive?
When the lift reaches 1st floor, 1 person gets out 3 people get in.
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 dies in the lift. How did I survive?
Hint:
Add Your Riddle Here
Have some tricky riddles of your own? Leave them below for our users to try and solve.