Three Rats Riddle
Three rats are sitting at the three corners of an equilateral triangle. Each rat starts randomly picks a direction and starts to move along the edge of the triangle. What is the probability that none of the rats collide?
Hint:
So lets think this through. The rats can only avoid a collision if they all decide to move in the same direction (either clockwise or rati-clockwise). If the rats do not pick the same direction, there will definitely be a collision. Each rat has the option to either move clockwise or rati-clockwise. There is a one in two chance that an rat decides to pick a particular direction. Using simple probability calculations, we can determine the probability of no collision. Did you answer this riddle correctly?
YES NO
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
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
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 Butcher Shop Clerk Riddle
A clerk at a butcher shop stands five feet ten inches tall and wears size 13 sneakers. What does he weigh?
Hint:
Going The Wrong Way
A truck driver is going down a one way street the wrong way, and passes at least ten cops. Why is he not caught?
Hint:
Because he was not driving! Hes walking on the sidewalk. Did you answer this riddle correctly?
YES NO
YES NO
Building A Wall
Hint:
Born In London Riddle
Simon Simpleton was born in London, England.
His mother was Welsh and his father Scottish.
When Simon was eight his mother died.
When Simon was ten his father married an Irish women and suddenly Simon had an Irish sister.
When Simon was twenty four he graduated as a lawyer and took a job in Edinburgh, Scotland.
He is now sixty six.
Why can he not be buried on the banks of Loch Lomond in his favorite village of Luss, in Bonnie Scotland?
His mother was Welsh and his father Scottish.
When Simon was eight his mother died.
When Simon was ten his father married an Irish women and suddenly Simon had an Irish sister.
When Simon was twenty four he graduated as a lawyer and took a job in Edinburgh, Scotland.
He is now sixty six.
Why can he not be buried on the banks of Loch Lomond in his favorite village of Luss, in Bonnie Scotland?
Hint:
Dollar-bills Riddle
Hint:
Age Of Three Daughters Riddles
I was visiting a friend one evening and remembered that he had three daughters. I asked him how old they were. The product of their ages is 72, he answered. Quizzically, I asked, Is there anything else you can tell me? Yes, he replied, the sum of their ages is equal to the number of my house. I stepped outside to see what the house number was. Upon returning inside, I said to my host, Im sorry, but I still cant figure out their ages. He responded apologetically, Im sorry, I forgot to mention that my oldest daughter likes strawberry shortcake. With this information, I was able to determine all three of their ages. How old is each daughter?
Hint:
3, 3, and 8. The only groups of 3 factors of 72 to have non-unique sums are 2 6 6 and 3 3 8 (with a sum of 14). The rest have unique sums:
2 + 2 + 18 = 22
2 + 3 + 12 = 18
2 + 4 + 9 = 15
3 + 4 + 6 = 13
The house number alone would have identified any of these groups. Since more information was required, we know the sum left the answer unknown. The presence of a single oldest child eliminates 2 6 6, leaving 3 3 8 as the only possible answer. Did you answer this riddle correctly?
YES NO
2 + 2 + 18 = 22
2 + 3 + 12 = 18
2 + 4 + 9 = 15
3 + 4 + 6 = 13
The house number alone would have identified any of these groups. Since more information was required, we know the sum left the answer unknown. The presence of a single oldest child eliminates 2 6 6, leaving 3 3 8 as the only possible answer. Did you answer this riddle correctly?
YES NO
Shoe Man Whistle
Hint:
The third equation has a term with a pair of whistles. The last line involves a single whistle.
Furthermore, the man in the second and third lines are wearing a whistle, but the man in the last line is not wearing a whistle. Presumably the value of the whistle should be accounted for to get the correct answer.
The pictures can be translated into the following equations:
shoes + shoes + shoes = 30
shoes + (man + whistle) + (man + whistle) = 20
(man + whistle) + 2(whistles) + 2(whistles) = 13
shoes + (man) x (whistle) = ?
From the first equation we can solve for the shoes value:
shoes + shoes + shoes = 30
3(shoes) = 30
shoes = 10
We can then solve the second equation for the (man + whistle) value:
shoes + (man + whistle) + (man + whistle) = 20
10 + 2(man + whistle) = 20
2(man + whistle) = 10
man + whistle = 5
Then we solve the third equation for the whistle:
(man + whistle) + 2(whistles) + 2(whistles) = 13
5 + 4(whistles) = 13
4(whistles) = 8
whistle = 2
We also need to solve for the value of the man:
man + whistle = 5
man + 2 = 5
man = 3
Now we can evaluate the final expression, remembering the order of operations that multiplication should be evaluated before addition:
shoes + (man) x (whistle) = ?
10 + 3 x 2
= 10 + 3 x 2
= 10 + 6
= 16 Did you answer this riddle correctly?
YES NO
Furthermore, the man in the second and third lines are wearing a whistle, but the man in the last line is not wearing a whistle. Presumably the value of the whistle should be accounted for to get the correct answer.
The pictures can be translated into the following equations:
shoes + shoes + shoes = 30
shoes + (man + whistle) + (man + whistle) = 20
(man + whistle) + 2(whistles) + 2(whistles) = 13
shoes + (man) x (whistle) = ?
From the first equation we can solve for the shoes value:
shoes + shoes + shoes = 30
3(shoes) = 30
shoes = 10
We can then solve the second equation for the (man + whistle) value:
shoes + (man + whistle) + (man + whistle) = 20
10 + 2(man + whistle) = 20
2(man + whistle) = 10
man + whistle = 5
Then we solve the third equation for the whistle:
(man + whistle) + 2(whistles) + 2(whistles) = 13
5 + 4(whistles) = 13
4(whistles) = 8
whistle = 2
We also need to solve for the value of the man:
man + whistle = 5
man + 2 = 5
man = 3
Now we can evaluate the final expression, remembering the order of operations that multiplication should be evaluated before addition:
shoes + (man) x (whistle) = ?
10 + 3 x 2
= 10 + 3 x 2
= 10 + 6
= 16 Did you answer this riddle correctly?
YES NO
12 = 6 And 6 = 3 Riddle
Hint:
12 (Twelve) has 6 letters,
6 (Six) has 3
Therefore,
10 (Ten) will be equal to 3 Did you answer this riddle correctly?
YES NO
6 (Six) has 3
Therefore,
10 (Ten) will be equal to 3 Did you answer this riddle correctly?
YES NO
17 Cows Riddle
One day, their neighbor came by to see how they were doing after their father's death. The three sons told him their problem. After thinking for a while, the neighbor said: "I'll be right back!" He went away, and when he came back, the three sons could divide the cows according to their father's will, and in such a way that each of them got a whole number of cows.
What was the neighbor's solution?
Hint:
The neighbour borrowed an extra cow, to make the total number of cows 18. Then the oldest son got 1/2 of 18 is 9 cows, the middle son got 1/3 of 18 is 6 cows, and the youngest son got 1/9 of 18 is 2 cows. Since 9+6+2 = 17, the cows could be divided among the three brothers in such a way that the borrowed cow was left over, and could be returned to its owner. Did you answer this riddle correctly?
YES NO
YES NO
I Am A 3 Digit Number Between 400 And 800 Riddle
Hint:
Witch Broom Wand Riddle
Hint:
Answer: 73 ...Broom - 3 (2nd picture compose of 2 brooms) that gives you 3+3+3+3 = 12 ...Wand - 7 (3 wands equal 21) ...Witch - 5 (15 each while carrying broom and wand giving you 45, so remove them in the last picture ...So 3 + (5x14) = 73 Did you answer this riddle correctly?
YES NO
YES NO
Add Your Riddle Here
Have some tricky riddles of your own? Leave them below for our users to try and solve.