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
Found In A Subway Riddle
I have seats but I'm not a living room
I have an engine but I'm not a car
I'm a mode of transport but I'm not an airplane
I'm sometimes a bullet but I'm not fired out of a gun
I can be found in a subway but Im not a sandwich.
What could I be?
I have an engine but I'm not a car
I'm a mode of transport but I'm not an airplane
I'm sometimes a bullet but I'm not fired out of a gun
I can be found in a subway but Im not a sandwich.
What could I be?
Hint:
The Train Of Love
A young man, living in Manhattan, New York, has two girlfriends. One lives to the North, in the Bronx, and the other lives to the South, in Brooklyn.
He likes both girls equally but can only visit one each weekend. He therefore leaves it to chance and takes the first train that arrives when he reaches the train station.
Even though the man arrives at a totally random time every Saturday morning and the Brooklyn and Bronx trains arrive equally often (every ten minutes), he finds himself visiting the girl in Brooklyn on average nine times out of ten. How could the odds so heavily favor taking the Brooklyn train?
He likes both girls equally but can only visit one each weekend. He therefore leaves it to chance and takes the first train that arrives when he reaches the train station.
Even though the man arrives at a totally random time every Saturday morning and the Brooklyn and Bronx trains arrive equally often (every ten minutes), he finds himself visiting the girl in Brooklyn on average nine times out of ten. How could the odds so heavily favor taking the Brooklyn train?
Hint: Think of a way the train schedules might favor one train over the other.
The Brooklyn train leaves exactly 1 minute before the Bronx train.
Let's say the Brooklyn train arrives at 09:00, 09:10, 09:20, etc. and the Bronx train arrives one minute after at 09:01, 09:11, 09:21, etc. Consider the ten minute interval from 09:00 to 09:10. If the man arrives between 09:00 and 09:01, the 09:01 Bronx train will be the first to arrive (assuming that he doesn't arrive at exactly 09:00). If the man arrives between 09:01 and 09:10, the 09:10 Brooklyn train will be the first to arrive. In any ten minute period, the Brooklyn train will be the first to arrive in nine of the ten minutes. Did you answer this riddle correctly?
YES NO
Let's say the Brooklyn train arrives at 09:00, 09:10, 09:20, etc. and the Bronx train arrives one minute after at 09:01, 09:11, 09:21, etc. Consider the ten minute interval from 09:00 to 09:10. If the man arrives between 09:00 and 09:01, the 09:01 Bronx train will be the first to arrive (assuming that he doesn't arrive at exactly 09:00). If the man arrives between 09:01 and 09:10, the 09:10 Brooklyn train will be the first to arrive. In any ten minute period, the Brooklyn train will be the first to arrive in nine of the ten minutes. Did you answer this riddle correctly?
YES NO
Two Girls On A Train
Two schoolgirls were traveling from the city to a dacha (summer cottage) on an electric train.
"I notice," one of the girls said "that the dacha trains coming in the opposite direction passes us every 5 minutes. What do you think-how many dacha trains arrive in the city in an hour, given equal speeds in both directions?"
"Twelve, of course," the other girl answered, "because 60 divided by 5 equals 12."
The first girl did not agree. What do you think?
"I notice," one of the girls said "that the dacha trains coming in the opposite direction passes us every 5 minutes. What do you think-how many dacha trains arrive in the city in an hour, given equal speeds in both directions?"
"Twelve, of course," the other girl answered, "because 60 divided by 5 equals 12."
The first girl did not agree. What do you think?
Hint:
If the girls had been on a standing train, the first girl's calculations would have been correct, but their train was moving. It took 5 minutes to meet a second train, but then it took the second train 5 more minutes to reach where the girls met the first train. So the time between trains is 10 minutes, not 5, and only 6 trains per hour arrive in the city. Did you answer this riddle correctly?
YES NO
YES NO
Who Is The Engineer Riddle
A train goes between Chicago and New York. The brakeman, the fireman and the engineer are named Smith, Jones and Brown. (The names are not necessarily in order). There are also three passengers named Mr. Smith, Mr. Jones and Mr. Brown. Mr. Brown lives in New York. The brakeman lives halfway between New York and Chicago. Mr. Jones earns exactly $20,000 per year. Smith beat the fireman at their last game of golf. The passenger who lives in Chicago has the same name as the brakeman. The brakeman's next door neighbor is a passenger on this train and earns exactly three times as much as the brakeman. What is the name of the engineer?
Hint:
Determine the known facts. Also notice that the passengers are noted with the title Mr., where as the brakeman, engineer and fireman are identified by their last names only. 1. Mr Brown Lives in New York City 2. The brakeman lives midway between NY and Chicago 3. Mr. Jones earns exactly $20K per year 4. Smith beat the fireman at their last game of golf. 5. The brakeman's next-door neighbor, who is a passenger, earns exactly three times the brakeman's salary. 6. The passenger who lives in Chicago has the same name as the brakeman. According to #1 and #2, the brakeman's neighbor cannot be Mr. Brown. According to #5, the brakeman's neighbor also cannot be Mr. Jones, because $20,000 is not evenly divisible by three. This leaves Mr. Smith as the next door neighbor to the brakeman. Mr. Smith lives halfway between New York and Chicago (#2) as does the brakeman. Since Mr. Brown lives in New York, by process of elimination, it is now known that Mr. Jones lives in Chicago. According to statement #6, this means that the brakeman is named Jones. According to statement #4, the fireman cannot be Smith, so the fireman must be must be Brown, which leaves Smith as the engineer. Did you answer this riddle correctly?
YES NO
YES NO
Red Suspenders Riddle
Hint:
Two Chemistry Students Walk Into A Bar
Two chemistry students walk into a bar.
The first says, "I'll order an H2O."
The second then says, "I'll order an H2O too."
Why did the second student die?
The first says, "I'll order an H2O."
The second then says, "I'll order an H2O too."
Why did the second student die?
Hint:
"H2O too" sounds like "H2O2", which is hydrogen peroxide. Hydrogen peroxide is a poison and can be deadly if its concentration in water is sufficiently high. Did you answer this riddle correctly?
YES NO
YES NO
Working After Being Fired Riddle
Hint:
Head In The Clouds Riddle
Head in the clouds but my feet on the earth
Glowing with fire, people kept a wide berth
Place full of stones, a bush and a rock
(Somewhere to hide, away from the shock)
I must not be touched and of heaven am token
I thundered loud when the tablets were broken
I am in the Bible - what am I?
Glowing with fire, people kept a wide berth
Place full of stones, a bush and a rock
(Somewhere to hide, away from the shock)
I must not be touched and of heaven am token
I thundered loud when the tablets were broken
I am in the Bible - what am I?
Hint:
High In The Sky Riddle
I was high in the sky but also firmly on the earth
I brought cooperation for many but confusion for all
I was unmissable by the crowd yet overlooked by the One
I was the world's first true skyscraper and also its last
I am in the Bible - what am I?
I brought cooperation for many but confusion for all
I was unmissable by the crowd yet overlooked by the One
I was the world's first true skyscraper and also its last
I am in the Bible - what am I?
Hint:
The Campfires Riddle
Hint:
Three Rooms Riddle
A murderer is condemned to death. He has to choose between three rooms. The first is full of raging fires, the second is full of assassins with loaded guns, and the third is full of lions that haven't eaten in 3 years.
Hint:
Couples Wait Until Marriage To Share This
Hint:
This Gate's Key Riddle
My first is foremost legally,
My second circles outwardly,
My third leads all in victory,
My fourth twice ends a nominee,
My whole is this gate's only key.
What am I?
My second circles outwardly,
My third leads all in victory,
My fourth twice ends a nominee,
My whole is this gate's only key.
What am I?
Hint:
God Bless America Riddle
Hint:
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