A Rickety Bridge Riddle
Four people need to cross a rickety bridge at night. Unfortunately, they have only one torch and the bridge is too dangerous to cross without one. The bridge is only strong enough to support two people at a time. Not all people take the same time to cross the bridge. Times for each person: 1 min, 2 mins, 7 mins and 10 mins. What is the shortest time needed for all four of them to cross the bridge?
Hint:
17 mins.
The initial solution most people will think of is to use the fastest person as an usher to guide everyone across. How long would that take? 10 + 1 + 7 + 1 + 2 = 21 mins. Is that it? No. That would make this question too simple even as a warm up question.
Let's brainstorm a little further. To reduce the amount of time, we should find a way for 10 and 7 to go together. If they cross together, then we need one of them to come back to get the others. That would not be ideal. How do we get around that? Maybe we can have 1 waiting on the other side to bring the torch back. Ahaa, we are getting closer. The fastest way to get 1 across and be back is to use 2 to usher 1 across. So let's put all this together.
1 and 2 go cross
2 comes back
7 and 10 go across
1 comes back
1 and 2 go across (done)
Total time = 2 + 2 + 10 + 1 + 2 = 17 mins Did you answer this riddle correctly?
YES NO
The initial solution most people will think of is to use the fastest person as an usher to guide everyone across. How long would that take? 10 + 1 + 7 + 1 + 2 = 21 mins. Is that it? No. That would make this question too simple even as a warm up question.
Let's brainstorm a little further. To reduce the amount of time, we should find a way for 10 and 7 to go together. If they cross together, then we need one of them to come back to get the others. That would not be ideal. How do we get around that? Maybe we can have 1 waiting on the other side to bring the torch back. Ahaa, we are getting closer. The fastest way to get 1 across and be back is to use 2 to usher 1 across. So let's put all this together.
1 and 2 go cross
2 comes back
7 and 10 go across
1 comes back
1 and 2 go across (done)
Total time = 2 + 2 + 10 + 1 + 2 = 17 mins Did you answer this riddle correctly?
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
John's Three Daughters Riddle
John has three daughters who are all unmarried. The youngest always lies, the oldest always tells the truth, and the one in the middle either tells the truth or lies. A very rich young man comes to John's house and says he wishes to marry one of his daughters. Naturally he wants to marry the oldest or the youngest so he will always know if she is lying or telling the truth. John agrees but says he can only ask one of the girls a yes or no question to decide which one he marries. They all look the same age.
What one question does he ask one of the daughters at random to figure out which daughter is the youngest or oldest?
What one question does he ask one of the daughters at random to figure out which daughter is the youngest or oldest?
Hint:
"Is she older than her?"
Explanation: (He would ask one of the daughters if one of the other daughters is older than the last daughter). He always should pick the younger daughter based on what he knows. If he asks the older daughter and she says yes, then the youngest daughter will be known. If he asks the older daughter and she says no, then the youngest daughter is the other one. If he asks the youngest daughter and she says yes, she is lying and he will still pick the oldest. If he asks the youngest and she says no, he will just pick the other like in the first case. If he asks the middle daughter it doesn't matter because both will be acceptable choices. Did you answer this riddle correctly?
YES NO
Explanation: (He would ask one of the daughters if one of the other daughters is older than the last daughter). He always should pick the younger daughter based on what he knows. If he asks the older daughter and she says yes, then the youngest daughter will be known. If he asks the older daughter and she says no, then the youngest daughter is the other one. If he asks the youngest daughter and she says yes, she is lying and he will still pick the oldest. If he asks the youngest and she says no, he will just pick the other like in the first case. If he asks the middle daughter it doesn't matter because both will be acceptable choices. Did you answer this riddle correctly?
YES NO
The Skyscraper Ring Riddle
Hint:
The man has survived a nuclear holocaust. He has wandered the earth for months looking for another survivor, but cannot find anyone and so comes to believe that he is the only survivor. Out of loneliness, he decides to commit suicide by jumping out of a tall building. When he is falling and hears the phone ring, he realizes that he must have been wrong- there IS another survivor. He has a heart attack and dies. Did you answer this riddle correctly?
YES NO
YES NO
Needing And Not Knowing Riddle
Riddle me this
The man who invented it doesn't want it. The man who bought it doesn't need it. The man who needs it doesn't know it. What is it?
The man who invented it doesn't want it. The man who bought it doesn't need it. The man who needs it doesn't know it. What is it?
Hint:
Sweet 16 Riddle
There is a man who is very rich. He has a daughter who is turning 16 and he wants to throw a party for her. He invited all the men in the kingdom. At the party the man invites everyone out to the pool. The pool is infested with salt water crocodiles. The rich man says, "Whoever can swim across this pool and come out alive, can either have 1 million dollars or marry my daughter." Then there was a splash! They looked over to see a man swimming across the pool with his clothes getting ripped apart. He gets to the end and jumps out. "Congratulations! Do you want to marry my daughter or $1,000,000! What did the man say?
Hint:
Neither. He wanted the name of the person that pushed him in. Did you answer this riddle correctly?
YES NO
YES NO
The One Story House Riddle
A drunk man came home riding in his car at night. Got to his home walked up the stairs in his one story house and turned off the light and fell asleep. When he woke up the next day he looked out the only window in the house and he saw something that scared him to death.
What scared him to death and how can he walk up on stairs in a one story house?
What scared him to death and how can he walk up on stairs in a one story house?
Hint:
How he can walk up stairs in a one story house is that he lived in a lighthouse and when he turned the only light off in the lighthouse all the boats crashed on the shore and he saw a boat coming toward him Did you answer this riddle correctly?
YES NO
YES NO
Swinging A Stick Riddle
A man is walking through a park in Mexico one day and sees a group of four boys standing in a circle. A smaller boy is holding a large stick and hands it to a larger boy saying "I couldn't do it, your turn."
The larger boy swings the stick twice and the other two boys fall to the ground. The smaller boy says "I'll get 'em next time." The man walks away smiling.
What just happened?
The larger boy swings the stick twice and the other two boys fall to the ground. The smaller boy says "I'll get 'em next time." The man walks away smiling.
What just happened?
Hint:
Black And Admired Riddle
Black we are and much admired,
men seek us if they are tired,
We tire the horse, comfort man,
guess this riddle if you can.
men seek us if they are tired,
We tire the horse, comfort man,
guess this riddle if you can.
Hint:
A Suitor To Portia Riddle
The casket scene in "The Merchant of Venice" contains several riddles. Which of these nobles was NOT a suitor to Portia? This odd-man-out noble might easily be confused with the contender who chose 'Who chooseth me shall gain what many men desire.'
Hint:
100 Floors Riddle
Hint:
He is short, so he can't reach the 100th floor button. On rainy days, he can use his umbrella to poke the button. Did you answer this riddle correctly?
YES NO
YES NO
A Bell Rings Riddle
Hint:
A man takes his blind friend swimming. The seeing man stands on the shore with a handbell to ring so that the blind man can find his way back to shore if he starts getting too far out. There is a buoy with a bell on it floating out far from shore. The blind man hears the buoy's bell and thinks it's his friend's bell so he follows the sound- further out in the water. The friend on shore sees what is happening and begins shouting and ringing his bell furiously. The blind man becomes exhausted out near the buoy and drowns.
A bell rings (the bell on the buoy)
a man cries (the seeing man cries as in shouting out, not sadness crying)
A bell rings (the bell of the seeing man)
a man dies (the blind swimmer) Did you answer this riddle correctly?
YES NO
A bell rings (the bell on the buoy)
a man cries (the seeing man cries as in shouting out, not sadness crying)
A bell rings (the bell of the seeing man)
a man dies (the blind swimmer) Did you answer this riddle correctly?
YES NO
The Tenth Floor Elevator Riddle
A man lives on the tenth floor of a building. Every day he takes the elevator to go down to the ground floor to go to work. When he returns he takes the same elevator to the seventh floor and walks up the stairs to reach his apartment on the tenth floor. He hates walking so why does he do it?
Note that there is nothing wrong with the elevator or the design of the building. It's a perfectly normal elevator in a perfectly normal building.
Note that there is nothing wrong with the elevator or the design of the building. It's a perfectly normal elevator in a perfectly normal building.
Hint: The elevator is perfectly normal and the design of the building is perfectly normal, but there is something different about the man.
The man is very short (i.e. a little person).
Because of his short stature, the man is unable to reach any higher than the button for the 7th floor (elevator floor number buttons are laid out in descending floor order from top to bottom). Did you answer this riddle correctly?
YES NO
Because of his short stature, the man is unable to reach any higher than the button for the 7th floor (elevator floor number buttons are laid out in descending floor order from top to bottom). Did you answer this riddle correctly?
YES NO
Under The Cup Riddle
You decide to play a game with your friend where your friend places a coin under one of three cups. Your friend would then switch the positions of two of the cups several times so that the coin under one of the cups moves with the cup it is under. You would then select the cup that you think the coin is under. If you won, you would receive the coin, but if you lost, you would have to pay.
As the game starts, you realise that you are really tired, and you don't focus very well on the moving of the cups. When your friend stops moving the cups and asks you where the coin is, you only remember a few things:
He put the coin in the rightmost cup at the start.
He switched two of the cups 3 times.
The first time he switched two of the cups, the rightmost one was switched with another.
The second time he switched two of the cups, the rightmost one was not touched.
The third and last time he switched two of the cups, the rightmost one was switched with another.
You don't want to end up paying your friend, so, using your head, you try to work out which cup is most likely to hold the coin, using the information you remember.
Which cup is most likely to hold the coin?
As the game starts, you realise that you are really tired, and you don't focus very well on the moving of the cups. When your friend stops moving the cups and asks you where the coin is, you only remember a few things:
He put the coin in the rightmost cup at the start.
He switched two of the cups 3 times.
The first time he switched two of the cups, the rightmost one was switched with another.
The second time he switched two of the cups, the rightmost one was not touched.
The third and last time he switched two of the cups, the rightmost one was switched with another.
You don't want to end up paying your friend, so, using your head, you try to work out which cup is most likely to hold the coin, using the information you remember.
Which cup is most likely to hold the coin?
Hint: Write down the possibilities. Remember that there are only three cups, so if the rightmost cup wasn't touched...
The rightmost cup.
The rightmost cup has a half chance of holding the coin, and the other cups have a quarter chance.
Pretend that Os represent cups, and Q represents the cup with the coin.
The game starts like this:
OOQ
Then your friend switches the rightmost cup with another, giving two possibilities, with equal chance:
OQO
QOO
Your friend then moves the cups again, but doesn't touch the rightmost cup. The only switch possible is with the leftmost cup and the middle cup. This gives two possibilities with equal chance:
QOO
OQO
Lastly, your friend switches the rightmost cup with another cup. If the first possibility shown above was true, there would be two possibilities, with equal chance:
OOQ
QOO
If the second possibility shown above (In the second switch) was true, there would be two possibilities with equal chance:
OOQ
OQO
This means there are four possibilities altogether, with equal chance:
OOQ
QOO
OOQ
OQO
This means each possibility equals to a quarter chance, and because there are two possibilities with the rightmost cup having the coin, there is a half chance that the coin is there. Did you answer this riddle correctly?
YES NO
The rightmost cup has a half chance of holding the coin, and the other cups have a quarter chance.
Pretend that Os represent cups, and Q represents the cup with the coin.
The game starts like this:
OOQ
Then your friend switches the rightmost cup with another, giving two possibilities, with equal chance:
OQO
QOO
Your friend then moves the cups again, but doesn't touch the rightmost cup. The only switch possible is with the leftmost cup and the middle cup. This gives two possibilities with equal chance:
QOO
OQO
Lastly, your friend switches the rightmost cup with another cup. If the first possibility shown above was true, there would be two possibilities, with equal chance:
OOQ
QOO
If the second possibility shown above (In the second switch) was true, there would be two possibilities with equal chance:
OOQ
OQO
This means there are four possibilities altogether, with equal chance:
OOQ
QOO
OOQ
OQO
This means each possibility equals to a quarter chance, and because there are two possibilities with the rightmost cup having the coin, there is a half chance that the coin is there. Did you answer this riddle correctly?
YES NO
Pearl Problems Riddle
"I'm a very rich man, so I've decided to give you some of my fortune. Do you see this bag? I have 5001 pearls inside it. 2501 of them are white, and 2500 of them are black. No, I am not racist. I'll let you take out any number of pearls from the bag without looking. If you take out the same number of black and white pearls, I will reward you with a number of gold bars equivalent to the number of pearls you took."
How many pearls should you take out to give yourself a good number of gold bars while still retaining a good chance of actually getting them?
How many pearls should you take out to give yourself a good number of gold bars while still retaining a good chance of actually getting them?
Hint: If you took out 2 pearls, you would have about a 50% chance of getting 2 gold bars. However, you can take even more pearls and still retain the 50% chance.
Take out 5000 pearls. If the remaining pearl is white, then you've won 5000 gold bars! Did you answer this riddle correctly?
YES NO
YES NO
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