Outrunning A Train Riddle
Walking home one day, you take a short cut along the train tracks. The tracks cross a narrow bridge over a deep gorge. At the point you are 3/8 of the way across the bridge, you hear the train whistle somewhere behind you. You charge across the bridge, and jump off the track as the train is about to run you down. As it happens, if you had gone the other way, you would have reached safety just before being run over as well. If you can run ten miles per hour, how fast is the train moving?
Hint:
The train is moving at 40 miles per hour. Imagine that a friend is walking with you. When the train whistle blows, you head away from the train, he heads toward it. When he reaches safety, you will be 6/8 (or 3/4)of the way across the bridge, and the train will have just reached the bridge. For the train to cross 4/4 of the bridge in the time you cross the remaining 1/4, the train must be moving four times your speed. Did you answer this riddle correctly?
YES NO
YES NO
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
Denver To Australia Riddle
You're the pilot an airplane, traveling from Denver, Colorado to Australia.
The plane is going 652 mph, taking four pit stops and facing severe weather conditions. On the fourth day the plane finally arrives on Australia and everyone on board enjoyed their flight. What is the pilot of the planes name?
The plane is going 652 mph, taking four pit stops and facing severe weather conditions. On the fourth day the plane finally arrives on Australia and everyone on board enjoyed their flight. What is the pilot of the planes name?
Hint:
Your the pilot of the plane! Re-read the first sentence... Did you answer this riddle correctly?
YES NO
YES NO
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
I Move As Fast As You Do
I am a great fitness teacher
Where my feet are replaced by wheels.
I move as fast as you do,
While sometimes faster than you.
Sometimes you ride on my back
To places you can't on huge vehicles,
And feed my legs with air
Then cycle down the road.
I am a?
Where my feet are replaced by wheels.
I move as fast as you do,
While sometimes faster than you.
Sometimes you ride on my back
To places you can't on huge vehicles,
And feed my legs with air
Then cycle down the road.
I am a?
Hint:
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
Poor Mr. Teddy
Poor Mr. Teddy was found dead in his study by Mr. Fiend.
Mr. Fiend recounted his dismal discovery to the police:
I was walking by Mr. Teddys house when I thought I would just pop in for a visit. I noticed his study light was on and I decided to peek in from the outside to see if he was in there. I walked through the snow towards the window, and I had to wipe the condensation off the window to see inside. That is when I saw his body. I kicked in the front door to confirm my suspicions of foul play. I called the police immediately afterward.
The officer immediately arrested Mr. Fiend for the murder of Mr. Teddy.
How did he know Mr. Fiend was lying?
Mr. Fiend recounted his dismal discovery to the police:
I was walking by Mr. Teddys house when I thought I would just pop in for a visit. I noticed his study light was on and I decided to peek in from the outside to see if he was in there. I walked through the snow towards the window, and I had to wipe the condensation off the window to see inside. That is when I saw his body. I kicked in the front door to confirm my suspicions of foul play. I called the police immediately afterward.
The officer immediately arrested Mr. Fiend for the murder of Mr. Teddy.
How did he know Mr. Fiend was lying?
Hint:
Condensation forms on the inside of the window in the winter, not on the outside. So Mr. Fiend could not have wiped it off to discover Mr. Teddys body. Did you answer this riddle correctly?
YES NO
YES NO
World War 1 Riddle
A grandfather is telling his grandson war stories.
At the end of World War 1, I was awarded for my bravery after saving a group of my men, the grandfather says. You see, we were fighting in northern France and one of our enemies threw a grenade at us. I managed to pick it up and throw it away before it exploded. So right after the war ended, a General gave me a sword, engraved with the words Awarded for Bravery and Valor, A True Hero, World War 1.
The grandson thinks about the story for a minute and then says Grandpa, that story can't be true! How did the grandson know?
At the end of World War 1, I was awarded for my bravery after saving a group of my men, the grandfather says. You see, we were fighting in northern France and one of our enemies threw a grenade at us. I managed to pick it up and throw it away before it exploded. So right after the war ended, a General gave me a sword, engraved with the words Awarded for Bravery and Valor, A True Hero, World War 1.
The grandson thinks about the story for a minute and then says Grandpa, that story can't be true! How did the grandson know?
Hint:
It was the only World War at that time and World War 2 had not started yet. Did you answer this riddle correctly?
YES NO
YES NO
Stolen Apple Riddle
Mrs. Stotch is a fifth grade teacher. One of her students took her apple. Mrs. Stotch has narrowed the suspects down to Billy, Paige, and Tyler. Each of the students give these statements:
Billy: I didnt do it.
Paige: I didnt do it.
Tyler: Paige did it!
Mrs. Stotch knows that only one of the kids is telling the truth. Who is telling the truth and who took the apple?
Billy: I didnt do it.
Paige: I didnt do it.
Tyler: Paige did it!
Mrs. Stotch knows that only one of the kids is telling the truth. Who is telling the truth and who took the apple?
Hint:
Billy did it. Paige is telling the truth so she didnt do it. Tyler is lying so he reinforces that Paige didnt do it. Billy is lying so he did it. Did you answer this riddle correctly?
YES NO
YES NO
A Man In The Shadows Riddle
Hint:
One Jump Ahead
I live in the street
I steal food
I was put in jail, only to get out
I met a beautiful girl,
I sing One Jump Ahead.
Who am I?
I steal food
I was put in jail, only to get out
I met a beautiful girl,
I sing One Jump Ahead.
Who am I?
Hint:
Living In China Riddle
I help a human who wants to help her dad,
I give her bad advice walking into camp,
I love doing stuff for my selfish purposes.
Who am I?
Hint:
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?
YES NO
YES NO
Pounds Of Sugar Riddle
The grocer had ten customers, each wanting to buy a 2 pound bag of sugar. A 20 pound bag of sugar had been delivered that morning, but he had not yet divided it because he could only find the 5lb and 9lb weights. One of the customers, getting impatient, showed him the quickest way to measure the sugar with the two weights he already had. How did he do it?
Hint:
Weigh out 4 pounds of sugar with the 5lb and the 9lb weights in different pans of the scales. With the 4lb weight , weigh three more lots of 4 pounds each - the remaining sugar will also weigh 4 pounds. Divide each 4 pound portion equally on the two sides of the scales. Did you answer this riddle correctly?
YES NO
YES NO
The Reckless Bus Driver Riddle
A bus driver was heading down a street in Colorado. He went right past a stop sign without stopping, he turned left where there was a "no left turn" sign, and he went the wrong way on a one-way street. Then he went on the left side of the road past a cop car. Still - he didn't break any traffic laws. Why not?
Hint:
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