The Secret Santa Exchange
A group of ten friends decide to exchange gifts as secret Santas. Each person writes his or her name on a piece of paper and puts it in a hat. Then each person randomly draws a name from the hat to determine who has him as his or her secret Santa. The secret Santa then makes a gift for the person whose name he drew.
When it's time to exchange presents, each person walks over to the person he made the gift for and holds his or her left hand in his right hand.
What is the probability that the 10 friends holding hands form a single continuous circle?
When it's time to exchange presents, each person walks over to the person he made the gift for and holds his or her left hand in his right hand.
What is the probability that the 10 friends holding hands form a single continuous circle?
Hint: It's not as difficult as it seems.
It's the number of ways the friends can form a circle divided by the number of ways the names can be drawn out of the hat.
1/10
For a group of n friends, there are n! (n factorial) ways to draw the names out of the hat. Since a circle does not have a beginning and end, choose one person as the beginning and end of the circle. There are now (n-1)! ways to distribute the remaining people around the circle. Thus the probability of forming a single circle is
(n-1)! / n!
Since n! = (n-1)! * n (for n > 1), this can be rewritten as
(n-1)! / (n*(n-1)!)
Factoring out the (n-1)! from the numerator and denominator leaves
1/n
as the probability. Did you answer this riddle correctly?
YES NO
For a group of n friends, there are n! (n factorial) ways to draw the names out of the hat. Since a circle does not have a beginning and end, choose one person as the beginning and end of the circle. There are now (n-1)! ways to distribute the remaining people around the circle. Thus the probability of forming a single circle is
(n-1)! / n!
Since n! = (n-1)! * n (for n > 1), this can be rewritten as
(n-1)! / (n*(n-1)!)
Factoring out the (n-1)! from the numerator and denominator leaves
1/n
as the probability. Did you answer this riddle correctly?
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
A Dark Room Riddle
If you had only one match, and entered a dark room containing an oil lamp, some newspaper, and some kindling wood, which would you light first?
Hint:
Invisible At Night Riddle
I fly like a bird of many colors through the sky. I am made with both wood and fire but I do not burn up. You can see me clearly during the day, but I am nearly invisible at night. What am I?
Hint:
Associated With Cob
Im yellow but Im not the sun
I grow in a field but Im not a sunflower
Im found on an ear but Im not a piece of jewelry
I go well with butter but Im not a slice of toast
Im associated with cob but Im not a web
What am I?
I grow in a field but Im not a sunflower
Im found on an ear but Im not a piece of jewelry
I go well with butter but Im not a slice of toast
Im associated with cob but Im not a web
What am I?
Hint:
Sweet And Bakes Riddle
I have eyes but I cant see
I have skin but I cant feel anything
I can be sweet but Im not a piece of candy
I can be baked but Im not a cake
I can be peeled but Im not a carrot
What could I be?
I have skin but I cant feel anything
I can be sweet but Im not a piece of candy
I can be baked but Im not a cake
I can be peeled but Im not a carrot
What could I be?
Hint:
A Prisoner Escaped From A Prison Riddle
Hint:
The man was more than halfway across a bridge when he spotted the police car, so the quickest way to leave the bridge was to run towards the police car and then turn and run into the woods to hide. Did you answer this riddle correctly?
YES NO
YES NO
Mark And Nancy Riddle
On a Saturday afternoon, the couple went out to a restaurant to celebrate their fifth anniversary together. Her when they returned in the evening, they found their son dead. There were three other people in the house at the time of the murder. The babysitter said she was ironing sams school uniform for tomorrow. The maid said she was cleaning the corners of the house and the chef said he was chopping vegetables for dinner. Youve been hired to investigate who killed Sam. So who did it?
Hint:
It can be the babysitter or the chef.
Explanation: Both of them are the culprit because if they went for dinner so why the chef is preparing dinner?
And the other is the babysitter because she was ironing the shirt for school tomorrow but it was a Saturday so the next day is Sunday. Did you answer this riddle correctly?
YES NO
Explanation: Both of them are the culprit because if they went for dinner so why the chef is preparing dinner?
And the other is the babysitter because she was ironing the shirt for school tomorrow but it was a Saturday so the next day is Sunday. Did you answer this riddle correctly?
YES NO
What Flattens All Mountains Riddle
Hint:
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