The Same Birthday
How many people do you need to have the odds be in favor (at least 50% chance) of two people having the same birthday?
Hint:
Eight Eights
Hint:
Find That Tennis Ball
You have 7 tennis balls that are all identical but one of them is slightly lighter than the others.
Using a balance scale and only two separate weightings, how can you find the light tennis ball?
Using a balance scale and only two separate weightings, how can you find the light tennis ball?
Hint:
Put three of the balls on each side. If they are even the ball that wasn't weighed is the light one. If they aren't even the side that is lighter has the light ball. Of these three balls, one should be put on each side. If the sides are even than the other ball is the light one. If they aren't even the one that is lighter is the ball you're looking for. Did you answer this riddle correctly?
YES NO
YES NO
Brownie Currency
You're going to a friends house and want to give them some brownies. On the way to their house you cross 5 bridges. At each bridge you must pay a toll of half of your brownies to the owner. But they are all very nice and give you back a brownie from what you give them.
How many brownies must you start with to give your friend 2 brownies?
How many brownies must you start with to give your friend 2 brownies?
Hint:
Just 2.
Each time you give the owner of a bridge half of your brownies (1 brownie) they give you one back as well. Did you answer this riddle correctly?
YES NO
Each time you give the owner of a bridge half of your brownies (1 brownie) they give you one back as well. Did you answer this riddle correctly?
YES NO
How Many Batteries?
You have a flashlight that takes 2 working batteries. You have 8 batteries but only 4 of them work.
What is the fewest number of pairs you need to test to guarantee you can get the flashlight on?
What is the fewest number of pairs you need to test to guarantee you can get the flashlight on?
Hint:
7. If you break the batteries into 3 groups: Two groups of 3 and one group of 2. By doing this you guarantee that one of the groups has 2 working batteries. Both of the groups of 3 have 3 possible combinations of 2 batteries and the group of 2 only has 1 combination. So, 3 + 3 + 1 = 7 tries at most to find two working batteries. Did you answer this riddle correctly?
YES NO
YES NO
Four Daughters
Hint:
A Knight To The Rescue
A knight comes to a castle where his love is trapped. The castle is surrounded by a square moat that is 10 feet wide (it forms a square around the castle). The knight is able to fashion two 9 foot long planks to cross the moat.
How can he do this?
How can he do this?
Hint:
He puts one plank across the corner of the square (where two sides meet) and puts the other perpendicular to it to form a 'T' shape in the corner allowing him to cross the moat and save his beloved. Did you answer this riddle correctly?
YES NO
YES NO
How Many Times A Day?
Hint:
22 times: 12:00:00, 1:05:27, 2:10:55, 3:16:22, 4:21:49, 5:27:16, 6:32:44, 7:38:11, 8:43:38, 9:49:05, 10:54:33. Each twice a day. Did you answer this riddle correctly?
YES NO
YES NO
A Nose That Grows
Every time a man lies his nose grows to 150 percent of its size. Every time he tells the truth it shrinks to 50 percent of its size.
What will happen if he alternates between lies and the truth
What will happen if he alternates between lies and the truth
Hint:
For every pair of a truth and a lie his nose will shrink to 75 percent of its previous size prior to this truth and lie. So the correct answer is 0. As the number of times he tells a lie and the truth ((3/4)n) approaches infinity the length of his nose approaches 0. Did you answer this riddle correctly?
YES NO
YES NO
Which Is Correct?
Hint: What is 9 plus 5?
1 Year Of Chickens
There are five hen and rooster pairs. Each pair has one baby every month.
How many chickens will there be in one year?
How many chickens will there be in one year?
Hint:
It is impossible to know because the chicken's babies could also have babies during this time.
Did you answer this riddle correctly?
YES NO
Did you answer this riddle correctly?
YES NO
The Broken Grandfather Clock
A grandfather has a broken grandfather clock that is off by a minute every hour (too fast). He figures out a way, while keeping it running at the same rate, to make the clock say the correct time twice a day.
How could he do this?
How could he do this?
Hint:
Whats The Temperature?
Hint:
273.15 degrees Celsius. When making conversions like this you must convert to the Kelvin scale since it is the only one that works on a scale beginning with 0. Did you answer this riddle correctly?
YES NO
YES NO
How Old Could He Be?
In 1940, a correspondent proposed the following question:
A man's age at death was one twenty-ninth of the year of his birth. How old was he in 1900?
A man's age at death was one twenty-ninth of the year of his birth. How old was he in 1900?
Hint:
He was 44 years old.
From the question you know the man died between 1900 and 1940. We also know his age at death (x) is one twenty-ninth of the year of his birth (29x). If you add his age at death to the year he was born you get the year he died (30x). Only one year between 1900 and 1940 is divisible by 30, 1920 (the year he died). The year he was born can now be found: 1920 * (29/30) = 1856. So in 1900 he was (1900 - 1856) = 44 years old. Did you answer this riddle correctly?
YES NO
From the question you know the man died between 1900 and 1940. We also know his age at death (x) is one twenty-ninth of the year of his birth (29x). If you add his age at death to the year he was born you get the year he died (30x). Only one year between 1900 and 1940 is divisible by 30, 1920 (the year he died). The year he was born can now be found: 1920 * (29/30) = 1856. So in 1900 he was (1900 - 1856) = 44 years old. Did you answer this riddle correctly?
YES NO
The 100 Pound Watermelon
How much water evaporated?
Hint:
50 pounds.
In the beginning it is 99 pounds water and 1 pound other stuff. At the end the 1 pound other stuff is 2 percent so the total weight is 50 pounds. 50 pounds - 1 pound other stuff = 49 pounds water. So 99 pounds - 49 pounds = 50 pounds water lost. Did you answer this riddle correctly?
YES NO
In the beginning it is 99 pounds water and 1 pound other stuff. At the end the 1 pound other stuff is 2 percent so the total weight is 50 pounds. 50 pounds - 1 pound other stuff = 49 pounds water. So 99 pounds - 49 pounds = 50 pounds water lost. Did you answer this riddle correctly?
YES NO
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