The Gardners Riddle
Gretchen and Henry were discussing their new neighbors, the Gardners. Gretchen mentioned that she met two of the daughters, and they each had blond hair.
"I have met all of the sisters," replied Henry, "and the probability that both of the girls you met would have had blond hair, assuming you were equally likely to meet any of the sisters, is exactly 50%. Do you know how many children there are?"
After thinking for a minute, Gretchen asks if the family is abnormally large. When Henry replies that it is not, Gretchen tells him how many girls are in the family. What number did she say?
"I have met all of the sisters," replied Henry, "and the probability that both of the girls you met would have had blond hair, assuming you were equally likely to meet any of the sisters, is exactly 50%. Do you know how many children there are?"
After thinking for a minute, Gretchen asks if the family is abnormally large. When Henry replies that it is not, Gretchen tells him how many girls are in the family. What number did she say?
Hint:
Gretchen said that there were 4 girls in the family, three of whom were blond.
This would make the probability that she saw two blonds (3/4) * (2/3), which equals 1/2.
Other numbers would work, but the next pair would lead to a rather large family. Did you answer this riddle correctly?
YES NO
This would make the probability that she saw two blonds (3/4) * (2/3), which equals 1/2.
Other numbers would work, but the next pair would lead to a rather large family. Did you answer this riddle correctly?
YES NO
Matching Socks Riddle
Mismatched Joe is in a pitch dark room selecting socks from his drawer. He has only six socks in his drawer, a mixture of black and white. If he chooses two socks, the chances that he draws out a white pair is 2/3. What are the chances that he draws out a black pair?
Hint: Three pairs of matching socks... maybe not!!!
He has a ZERO chance of drawing out a black pair.
Since there is a 2/3 chance of drawing a white pair, then there MUST be 5 white socks and only 1 black sock. The chances of drawing two whites would thus be: 5/6 x 4/5 = 2/3 . With only 1 black sock, there is no chance of drawing a black pair. Did you answer this riddle correctly?
YES NO
Since there is a 2/3 chance of drawing a white pair, then there MUST be 5 white socks and only 1 black sock. The chances of drawing two whites would thus be: 5/6 x 4/5 = 2/3 . With only 1 black sock, there is no chance of drawing a black pair. 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
Two In A Row Riddle
A certain mathematician, his wife, and their teenage son all play a fair game of chess. One day when the son asked his father for 10 dollars for a Saturday night date, his father puffed his pipe for a moment and replied, "Let's do it this way. Today is Wednesday. You will play a game of chess tonight, tomorrow, and a third on Friday. If you win two games in a row, you get the money."
"Whom do I play first, you or mom?"
"You may have your choice," said the mathematician, his eyes twinkling.
The son knew that his father played a stronger game than his mother. To maximize his chance of winning two games in succession, should he play father-mother-father or mother-father-mother?
"Whom do I play first, you or mom?"
"You may have your choice," said the mathematician, his eyes twinkling.
The son knew that his father played a stronger game than his mother. To maximize his chance of winning two games in succession, should he play father-mother-father or mother-father-mother?
Hint: Who does he need to beat to win?
Father-mother-father
To beat two games in a row, it is necessary to win the second game. This means that it would be to his advantage to play the second game against the weaker player. Though he plays his father twice, he has a higher chance of winning by playing his mother second. Did you answer this riddle correctly?
YES NO
To beat two games in a row, it is necessary to win the second game. This means that it would be to his advantage to play the second game against the weaker player. Though he plays his father twice, he has a higher chance of winning by playing his mother second. 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
1 + 1 = 3 Riddle
Hint:
30 Sacks Of Coconuts
An intelligent trader travels from one place to another with 3 sacks having 30 coconuts each. No sack can hold more than 30 coconuts. On the way, he passes 30 check points. At each check point, he has to give one coconut for every sack he is carrying. What is the maximum number of coconuts that he can have with him at the end of his journey?
Hint:
He will have 25 coconuts with him at the end. The trick is to reduce the number of sacks as you pass checkpoints.
The first 10 checkpoints require 3 coconuts each, which empties his first sack. The next 15 checkpoints require 2 coconuts each, which will empty his second stack. Now, he is left with 1 sack and 5 more checkpoints. So, the 5 checkpoints will take 1 coconut each. Therefore, he will be left with 25 coconuts. Did you answer this riddle correctly?
YES NO
The first 10 checkpoints require 3 coconuts each, which empties his first sack. The next 15 checkpoints require 2 coconuts each, which will empty his second stack. Now, he is left with 1 sack and 5 more checkpoints. So, the 5 checkpoints will take 1 coconut each. Therefore, he will be left with 25 coconuts. Did you answer this riddle correctly?
YES NO
Coconut Toll Booth Riddle
There is a beautiful garden surrounded with water on three sides and only one road leading to it. This garden has thousands of coconut trees. Anyone can visit to pick coconuts.
The coconuts can be taken in boxes only. Each box can carry 20 coconuts.You can take as many boxes as you like for free but there are ten toll barriers on the road. Each toll booth collects tax in the form of you guessed it: coconuts. The number of coconuts taken is equal to the number of boxes. For example if you are carrying 50 boxes of coconut you have to pay 50 coconuts at each barrier.
If you took 10 boxes filled with coconuts from garden, tell me how many coconuts would you have remaining after crossing all ten toll booths?
The coconuts can be taken in boxes only. Each box can carry 20 coconuts.You can take as many boxes as you like for free but there are ten toll barriers on the road. Each toll booth collects tax in the form of you guessed it: coconuts. The number of coconuts taken is equal to the number of boxes. For example if you are carrying 50 boxes of coconut you have to pay 50 coconuts at each barrier.
If you took 10 boxes filled with coconuts from garden, tell me how many coconuts would you have remaining after crossing all ten toll booths?
Hint:
I Can Be Grand Riddle
I am a type of instrument
That can be grand or upright
I have hammers, strings and pedals
And my keys are black and white
That can be grand or upright
I have hammers, strings and pedals
And my keys are black and white
Hint:
A Type Of Flower Riddle
Hint:
Mortal Privation Riddle
Marking mortal privation, when firmly in place.
An enduring summation, inscribed in my face.
What am I?
An enduring summation, inscribed in my face.
What am I?
Hint:
Born In Mourning
I have a name, but it isn't my name. My face shows signs of age. I always mean the same thing, no matter what I say. I'm born in mourning, and I last 'til the end of days. Men plant me, but I never grow. They run from me, but I never move. They look at me and see their future, rotting in the fields where I bloom. What am I?
Hint:
Protect And Destroy
I am called white. My duty is to protect and destroy. All it takes is a sneeze and I will destroy... at the sign of a cut, I will come to protect. I will fight to my death... no matter how insignificant it may be. I am very helpful yet you can't see me. What am i?
Hint:
Favorite Drink Riddle
A man goes out drinking every night, returning to his home in the wee hours of every morning. No matter how much he drinks, he never gets a hangover. This drink is very well known, but is rarely consumed, served warm and taken straight from its source. The man is a sucker for a free drink, especially since he can't live without it. What is his favorite drink?
Hint:
Five Prom Couples Riddle
Five couples went to the prom as a group. The boys' names were Mark, Quintin, Jim, Bob, and James. The girls' names were Amanda, Betty, Susan, Jessica, and Jasmin. Each couple wore matching colors of either blue, yellow, red, green, or pink. Match the dates and the color they are wearing.
1) Two couples have the same first letter in their name. One of those letters is "B".
2) Susan wore red and Jessica wore blue.
3) Susan has more letters in her name than her date does.
4) Neither Mark nor Quintin went with Jasmin, who was wearing yellow.
5) Amanda went with Jim and they did not wear green.
1) Two couples have the same first letter in their name. One of those letters is "B".
2) Susan wore red and Jessica wore blue.
3) Susan has more letters in her name than her date does.
4) Neither Mark nor Quintin went with Jasmin, who was wearing yellow.
5) Amanda went with Jim and they did not wear green.
Hint:
Mark and Susan wore red.
Quintin and Jessica wore blue.
Jim and Amanda wore pink.
Bob and Betty wore green.
James and Jasmin wore yellow. Did you answer this riddle correctly?
YES NO
Quintin and Jessica wore blue.
Jim and Amanda wore pink.
Bob and Betty wore green.
James and Jasmin wore yellow. Did you answer this riddle correctly?
YES NO
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