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
Coffee Diner Riddle
A man walks into a diner and sits down. There's a new waitress working that he's never seen before. When she comes to his table to take his order, he says "Just a cup of coffee please." A few minutes later the waitress brings the man his coffee and heads back to the kitchen. A short while later, the man notices that there is a fly in his coffee and calls the waitress back. He asks her nicely to bring him another cup. The waitress brings the man's cup of coffee back to the kitchen and returns a few moments later. "Here you are, I poured you a new cup of coffee, no fly this time" she says and hands him the cup. The waitress turns around and starts to head back to the kitchen. She only takes a few steps before she hears the man shout out "Hey, this is the same cup of coffee, all you did was remove the fly!"
Assuming the coffee was still hot, how did the man know it was the same cup of coffee?
Assuming the coffee was still hot, how did the man know it was the same cup of coffee?
Hint: A man walks into a diner and sits down. There's a new waitress working that he's never seen before. When she comes to his table to take his order, he says "Just a cup of coffee please." A few minutes later the waitress brings the man his coffee and heads
Because the coffee was sweet. The man had added sugar to his coffee before noticing the fly. When the waitress brought him the "new" cup of coffee, he took a sip (to check whether it was in fact a newly poured cup of coffee) and noticed that the coffee was "already" sweet. Did you answer this riddle correctly?
YES NO
YES NO
Captured By The Riddler
In the land of Geopolizza, three men were captured by the infamous Riddler. So, the Riddler buries the three men, named 1, 2 and 3 in such a manner, that 1 is in the front, 2 in the middle and 3 in the back. They are buried neck deep, and cannot move, not even their heads. He shows them 5 caps, two of which are red and 3 of them are white. He then switches off the lights and places a hat on top of their heads. The situation is such that no one can see their hat color, 1 is facing the wall and cant say anything, 2 can see 1 and 3 can see both 1 and 2. Then he tells the rules of his game: "If either of you three can tell the correct color of your head, I will let all of you go. However, if any of you answer wrong, all 3 of you will instantly die. Time is 3 minutes."
Upon 2 and half minutes passing, A shouts the answer and all 3 are released free. How did he know the correct answer ?
Upon 2 and half minutes passing, A shouts the answer and all 3 are released free. How did he know the correct answer ?
Hint:
P3 can only be certain of his cap if 1 & 2 are both white. Since he is not certain then 1 & 2 must be either white/red or red/red. 2 knows this but the only combination that he will be able to know the colour of his own cap is if he sees that 1 is wearing a white cap. 1 knows this but as 2 remains uncertain then 1 must be wearing a red cap. 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:
Stay Out Of His Way Riddle
I don't like to wash my hands, or sing and dance.
I play the organ in a very different way.
I have to share a cottage with six other people.
And I don't always have a very nice attitude.
So you better stay out of my way!
Who am I? Body parts remaining: 6
I play the organ in a very different way.
I have to share a cottage with six other people.
And I don't always have a very nice attitude.
So you better stay out of my way!
Who am I? Body parts remaining: 6
Hint:
A Walk In The Desert Riddle
Four men walk into the desert. Suddenly all four are simultaneously knocked out. They awake buried to their heads in the sand unable to look anywhere but straight ahead. They are positioned so that each man sees another's head before him. However between the first and second man there is a separating wall.
So the first man sees only desert. The second man sees only wall. The third man sees another's head and a wall. The fourth man sees two heads and a wall. On top of each mans head is a hat. The underside of each cap is black, but the outside of each cap is either blue or white. Before any of the men can speak, their captors tell them if they speak, they die. However, if any of them can guess the color of their cap on the first try they go free. The captors tell them that there are two blue caps and two white caps.
Being an omniscient observer of the situation, we know that the order of the caps are: blue, white, blue, white. So knowing the perspective of each man in the sand, and that they can only see the color of caps/wall/desert in front of them, which of the four men knows for certain the color of his own cap. More importantly: why?
So the first man sees only desert. The second man sees only wall. The third man sees another's head and a wall. The fourth man sees two heads and a wall. On top of each mans head is a hat. The underside of each cap is black, but the outside of each cap is either blue or white. Before any of the men can speak, their captors tell them if they speak, they die. However, if any of them can guess the color of their cap on the first try they go free. The captors tell them that there are two blue caps and two white caps.
Being an omniscient observer of the situation, we know that the order of the caps are: blue, white, blue, white. So knowing the perspective of each man in the sand, and that they can only see the color of caps/wall/desert in front of them, which of the four men knows for certain the color of his own cap. More importantly: why?
Hint:
The third man. This is because he knows there are only two of each color cap. If the man behind him (the fourth man) saw two caps that were the same color in front of him, he would know that his own must be the opposite. However, because the caps alternate in color. The fourth man has only a 50% chance of getting his hat color correct, so therefore he stays quiet. The third man realizes that the fourth man is quiet because he must not see two caps of the same color in front of him, otherwise the fourth man would say the opposite of the caps in front of him. Therefore, the third man presumes his own cap must be the opposite of the mans in front of him, and his presumption is correct. Under this same logic, after the third man speaks his color hat, the second man, even though he sees only wall, would be the next to go free, because he knows his cap must be the opposite of whichever color the third mans cap was. Did you answer this riddle correctly?
YES NO
YES NO
Running Through Fields And Woods Riddle
Riddle me this
I run over fields and woods all day. Under the bed at night I sit, never alone. My tongue hangs out, up and to the rear, waiting to be filled in the morning. What am I?
I run over fields and woods all day. Under the bed at night I sit, never alone. My tongue hangs out, up and to the rear, waiting to be filled in the morning. What am I?
Hint:
Jealousy Wants Me Killed Riddle
Seven tiny people found me
Lying in their bed
Jealousy wants to have me killed
For my beauty she so dreads
The bite of an apple sent me to slumber
An evil trick gone amiss
Awaken from an endless sleep
By a charming Prince and a simple kiss
Who am I?
Lying in their bed
Jealousy wants to have me killed
For my beauty she so dreads
The bite of an apple sent me to slumber
An evil trick gone amiss
Awaken from an endless sleep
By a charming Prince and a simple kiss
Who am I?
Hint:
Dopey's Crayons Riddle
Hint:
Jail Dwarfs Riddle
Hint:
Cheering Up Dwarves Riddle
Hint:
Grumpy's Favorite Fruit Riddle
Hint:
7 Little Friends Riddle
Hint:
Hiding In The Woods
Hint:
Seven Dents Riddle
Hint:
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