The Last Cookie Riddle
Mike and James are arguing over who gets the last cookie in the jar, so their dad decides to create a game to settle their dispute. First, Mike flips a coin twice, and each time James calls heads or tails in the air. If James gets both calls right, he gets the last cookie. If not, Mike picks a number between one and six and then rolls a die. If he gets the number right, he gets the last cookie. If not, James picks two numbers between one and five, then spins a spinner with numbers one through five on it. If the spinner lands on one of James' two numbers, he gets the last cookie. If not, Mike does.
Who is more likely to win the last cookie, Mike or James? And what is the probability that person wins it?
Who is more likely to win the last cookie, Mike or James? And what is the probability that person wins it?
Hint: Their dad is a very smart person.
Believe it or not, both Mike and James have a 1/2 chance of winning.
James wins if:
-he calls both coin flips right = 1/2 x 1/2 = 1/4
OR
-he does not call both coin flips right, Mike does not call the die roll correctly, and he guesses the number on the spinner right = 3/4 x 5/6 x 2/5 = 30/120 = 1/4
1/4 + 1/4 = 1/2
Mike wins if:
-James does not call both coin flips right and he calls the die roll correctly = 3/4 x 1/6 = 3/24 = 1/8
OR
-James does not call both coin flips right, he does not call the die roll correctly, and Mike does not guess the number on the spinner right = 3/4 x 5/6 x 3/5 = 45/120 = 3/8
1/8 + 3/8 = 1/2
Of course, dad could have just flipped a coin Did you answer this riddle correctly?
YES NO
James wins if:
-he calls both coin flips right = 1/2 x 1/2 = 1/4
OR
-he does not call both coin flips right, Mike does not call the die roll correctly, and he guesses the number on the spinner right = 3/4 x 5/6 x 2/5 = 30/120 = 1/4
1/4 + 1/4 = 1/2
Mike wins if:
-James does not call both coin flips right and he calls the die roll correctly = 3/4 x 1/6 = 3/24 = 1/8
OR
-James does not call both coin flips right, he does not call the die roll correctly, and Mike does not guess the number on the spinner right = 3/4 x 5/6 x 3/5 = 45/120 = 3/8
1/8 + 3/8 = 1/2
Of course, dad could have just flipped a coin Did you answer this riddle correctly?
YES NO
The Coin Toss Riddle
You are in a bar having a drink with an old friend when he proposes a wager.
"Want to play a game?" he asks.
"Sure, why not?" you reply.
"Ok, here's how it works. You choose three possible outcomes of a coin toss, either HHH, TTT, HHT or whatever. I will do likewise. I will then start flipping the coin continuously until either one of our combinations comes up. The person whose combination comes up first is the winner. And to prove I'm not the cheating little weasel you're always making me out to be, I'll even let you go first so you have more combinations to choose from. So how about it? Is $10.00 a fair bet?"
You know that your friend is a skilled trickster and usually has a trick or two up his sleeve but maybe he's being honest this time. Maybe this is a fair bet. While you try and think of which combination is most likely to come up first, you suddenly hit upon a strategy which will be immensely beneficial to you. What is it?
"Want to play a game?" he asks.
"Sure, why not?" you reply.
"Ok, here's how it works. You choose three possible outcomes of a coin toss, either HHH, TTT, HHT or whatever. I will do likewise. I will then start flipping the coin continuously until either one of our combinations comes up. The person whose combination comes up first is the winner. And to prove I'm not the cheating little weasel you're always making me out to be, I'll even let you go first so you have more combinations to choose from. So how about it? Is $10.00 a fair bet?"
You know that your friend is a skilled trickster and usually has a trick or two up his sleeve but maybe he's being honest this time. Maybe this is a fair bet. While you try and think of which combination is most likely to come up first, you suddenly hit upon a strategy which will be immensely beneficial to you. What is it?
Hint: Think what would be most likely to happen if you chose HHH, would this be a good decision?
The answer is to let your friend go first. This puzzle is based on an old game/scam called Penny Ante. No matter what you picked, your friend would be able to come up with a combination which would be more likely to beat yours. For example, if you were to choose HHH, then unless HHH was the first combination to come up you would eventually lose since as soon as a Tails came up, the combination THH would inevitably come up before HHH. The basic formula you can use for working out which combination you should choose is as follows. Simply take his combination (eg. HHT) take the last term in his combination, put it at the front (in this case making THH) and your combination will be more likely to come up first. Try it on your friends! Did you answer this riddle correctly?
YES NO
YES NO
The Prime Number Riddle
Two hundred people in an auditorium are asked to think of a single digit number from 1 to 9 inclusive and write it down. All those who wrote down a prime number are now asked to leave. Ninety people remain behind in the hall. How many of these are expected to have written down an odd number?
Hint: Remember that 1 is not a prime number.
Those that remain behind must have written {1,4,6,8,9} and from this only {1,9} are odd. The probability of an odd number is thus 2/5.
Expected number of odds is 2/5 * 90 = 36 Did you answer this riddle correctly?
YES NO
Expected number of odds is 2/5 * 90 = 36 Did you answer this riddle correctly?
YES NO
An Absentminded Philosopher Riddle
An absentminded philosopher forgot to wind up the only clock in his house. He had no radio, television, telephone, internet, or any other means of ascertaining the time. He therefore decided to travel by foot to his friend's house, a few miles down a straight desert road. He stayed there for the night and when he came back home the following morning, he was able to set his clock to the correct time. Assuming the philosopher always walks at the same speed, how did he know the exact time upon his return? Note: this is not a trick question. The Philosopher did not bring anything to his friend's house, nor did he bring anything back with him on his trip home.
Hint: We can assume that the journey to his friend's and back took exactly the same amount of time.
He Philosopher winds the grandfather clock to a random time right before leaving, 9:00 for example. Although this is not the right time, the clock can now be used to measure elapsed time. As soon as he arrives at his friend's house, the Philosopher looks at the time on his friend's clock. Let's say the time is 7:15. He stays overnight and then, before leaving in the morning, he looks at the clock one more time. Let's say the time is now 10:15 (15 hours later). When the Philosopher arrives home, he looks at his grandfather clock. Let's say his clock reads 12:40. By subtracting the time he set it to when he left (9:00) from the current time (12:40) he knows that he has been gone for 15 hours and 40 minutes. He knows that he spent 15 hours at his friends house, so that means he spent 40 minutes walking. Since he walked at the same speed both ways, it took him 20 minutes to walk from his friend's home back to his place. So the correct time to set the clock to in this example would therefore be 10:15 (the time he left his friend's house) + 20 minutes (the time it took him to walk home) = 10:35. Did you answer this riddle correctly?
YES NO
YES NO
Cold Weather Riddle
Snow comes under the sky bright,
Hail could come in the long night.
But something between is a true fright!
After, it remains in sight.
Encounter it and it's right back to night.
For you, at least.
What am I?
Hail could come in the long night.
But something between is a true fright!
After, it remains in sight.
Encounter it and it's right back to night.
For you, at least.
What am I?
Hint: I'm a weather condition.
In 1990 A Person Is 15 Years Old Riddle
Hint:
The years are in B.C (Before Christ).
Thus, 1990 in BC will gives 15 years old and 1995 in BC will gives 10 years old. Did you answer this riddle correctly?
YES NO
Thus, 1990 in BC will gives 15 years old and 1995 in BC will gives 10 years old. Did you answer this riddle correctly?
YES NO
Three People At A Bus Stop Riddle
You're driving down the road in your car on a wild and stormy night. The weather is like a hurricane, with heavy rains, high winds, and lightning flashing constantly. While driving, you come across a partially-covered bus stop, and you can see three people waiting for a bus:
1. An old woman who looks as if she is about to die.
2. An old friend who once saved your life.
3.The perfect partner you have been dreaming about (your soulmate).
Knowing that you only have room for one passenger in your car (its a really small car), which one would you choose to offer a ride to? And why?
1. An old woman who looks as if she is about to die.
2. An old friend who once saved your life.
3.The perfect partner you have been dreaming about (your soulmate).
Knowing that you only have room for one passenger in your car (its a really small car), which one would you choose to offer a ride to? And why?
Hint:
I would give the car keys to my old friend, and let him take the old woman to the hospital. Then I would stay behind and wait for the bus with the partner of my dreams. Did you answer this riddle correctly?
YES NO
YES NO
A Man Is Sitting In A House At Night That Has No Lights
A man is sitting in a house at night that has no lights on at all. There is no lamp, no candle, nothing. Yet he is reading. How?
Hint:
Alex And The New Neighbor Riddle
So Alex and his friends are hanging out in his front yard one day, and they notice the house next to them has been sold and somebody new has moved in. Alex and his friends decide they want to greet the person the next day.
So it is the next day. Before they leave, Alex's mother asks them what they are doing, but since Alex despises his mom and doesn't like to talk to her, he just answer with "we are going to the new neighbor, can you leave us alone?" She says "who is the new neighbor." But Alex tells her to shut up and they leave.
They ring the doorbell, the neighbor comes outside, and Alex says hello and then the neighbors name. So what is the neighbors name?
So it is the next day. Before they leave, Alex's mother asks them what they are doing, but since Alex despises his mom and doesn't like to talk to her, he just answer with "we are going to the new neighbor, can you leave us alone?" She says "who is the new neighbor." But Alex tells her to shut up and they leave.
They ring the doorbell, the neighbor comes outside, and Alex says hello and then the neighbors name. So what is the neighbors name?
Hint:
The new neighbors name is 'Who.' ...When the mom SUPPOSEDLY asked "Who is the new neighbor?", she wasn't asking; she was making a statement. "Who is [the name of] the new neighbor." Did you answer this riddle correctly?
YES NO
YES NO
Prisoner Hat Riddle
Four inmates are cleaning up a littered beach as part of a prisoner work program. The warden, who happens to be overseeing the work, decides to play a little game with the prisoners. He tells them that if they win the game he will let them go free! He then proceeds to bury each prisoner up to his neck in sand as shown.
There is a wall between prisoners C and D (which cannot be seen through or around). Prisoner A can see prisoners B and C (by moving his head to the side). Prisoner B can see prisoner C. Prisoners C and D see only the wall.
The prisoners are immobilized in the ground and can't twist their body to see the person behind them. The warden shows them two black hats and two white hats and then puts the hats in a bag to conceal them. He then stands behind each prisoner, chooses a hat from the bag, and puts it on their head. The color of each prisoner's hat is shown in the image above.
The rules are simple. If any prisoner can figure out the color of the hat on his head, all four prisoners will be set free. But they must be sure, if one of them simply guesses and is wrong, they will all be shot dead! The prisoners are not allowed to talk to each other and they have 10 seconds.
The warden counts down "ten, nine, eight, seven". All four prisoners are silent. The warden smiles, knowing that he put the hats on in such a way that no prisoner could possibly know the color of the hat they had on. He continues "six, five, four, thr.."
"I know the color of my hat!" one of the prisoners finally blurts out.
Which prisoner called out and why is he 100% certain of the color of his hat?
There is a wall between prisoners C and D (which cannot be seen through or around). Prisoner A can see prisoners B and C (by moving his head to the side). Prisoner B can see prisoner C. Prisoners C and D see only the wall.
The prisoners are immobilized in the ground and can't twist their body to see the person behind them. The warden shows them two black hats and two white hats and then puts the hats in a bag to conceal them. He then stands behind each prisoner, chooses a hat from the bag, and puts it on their head. The color of each prisoner's hat is shown in the image above.
The rules are simple. If any prisoner can figure out the color of the hat on his head, all four prisoners will be set free. But they must be sure, if one of them simply guesses and is wrong, they will all be shot dead! The prisoners are not allowed to talk to each other and they have 10 seconds.
The warden counts down "ten, nine, eight, seven". All four prisoners are silent. The warden smiles, knowing that he put the hats on in such a way that no prisoner could possibly know the color of the hat they had on. He continues "six, five, four, thr.."
"I know the color of my hat!" one of the prisoners finally blurts out.
Which prisoner called out and why is he 100% certain of the color of his hat?
Hint:
Prisoner B.
If prisoners B and C had the same color hat on, prisoner A would have know immediately that his hat was the other color (there are only two hats of each color). Since prisoner A was silent, prisoners B and C must have different colored hats. Prisoner B realized this and knew that his hat was not the same color as prisoner C, therefore his hat must be black! Did you answer this riddle correctly?
YES NO
If prisoners B and C had the same color hat on, prisoner A would have know immediately that his hat was the other color (there are only two hats of each color). Since prisoner A was silent, prisoners B and C must have different colored hats. Prisoner B realized this and knew that his hat was not the same color as prisoner C, therefore his hat must be black! Did you answer this riddle correctly?
YES NO
Five Apples Riddle
There were five women sitting in a room. In the same room there was a basket with five apples in it. Each woman took an apple, but one apple still remained in the basket. How could this be?
Hint:
The fifth woman took the entire basket, with the apple still in it. Did you answer this riddle correctly?
YES NO
YES NO
Rivers With No Water Riddle
Hint: I represent an area of land or sea.
All Things Devours Riddle
This thing all things devours, birds, beasts, trees, flowers.
Gnaws iron, bites steel,
Grinds hard stone to meal.
Slays kings, ruins towns,
and beats high
Mountains Down
Gnaws iron, bites steel,
Grinds hard stone to meal.
Slays kings, ruins towns,
and beats high
Mountains Down
Hint: I'm free but also priceless.
Longest Human Nose Riddle
Hint:
It Follows A River While Standing Still
Hint:
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