The Bear
A bear walks south for one kilometer, then it walks west for one kilometer, then it walks
north for one kilometer and ends up at the same point from which it started. What color was
the bear?
The Chicken and Egg Problem
A chicken farmer has figured out that a hen and a half can lay an egg and a half in a day
and a half. How many hens does the farmer need to produce one dozen eggs in six days?
The Bacteriologist
A scientist is experimenting with bacteria that are one micron in diameter and that
reproduce by dividing every minute into two bacteria. At 12:00 PM, she puts a single
organism in a container. At precisely 1:00 PM, the container is full.
At what time was the container half full?
How big was the container?
The Missing Dollar
Three students checked into a hotel and paid the clerk $30 for a room ($10 each). When the
hotel manager returned, he noticed that the clerk had incorrectly charged $30 instead of
$25 for the room. The manager told the clerk to return $5 to the students. The clerk,
knowing that the students would not be able to divide $5 evenly, decided to keep $2 and to
give them only $3.
The students were very happy because they paid only $27 for the room ($9 each).
However, if they paid $27 and the clerk kept $2, that adds up to $29. What happened to the
other Dollar?
Melanesia and Polynesia
Fiji (in Melanesia) and American Samoa (in Polynesia) are two islands in the South Pacific
Ocean. Fiji is about 970 kilometers (600 miles) west of American Samoa. A small airplane
can fly this distance in two hours.
When will you arrive in Fiji if you leave American Samoa on a small airplane on Tuesday
night at 11:30 PM?
I predict that your result will be 18
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Think of a number.
Add 7 to it.
Subtract 2.
Subtract your original number.
Multiply by 4.
Subtract 2.
The Bermuda Triangle and the Mysterious Square
The Bermuda Triangle is a place in the Atlantic Ocean where ships and airplanes supposedly
disappear without a trace. In the picture below, a square appears when we rearrange the
pieces of the upper triangle to form the lower triangle. The pieces in both pictures are
identical. Can you explain the origin of the square? You will need your knowledge of
geometry to solve this problem.
The Wanderer
You start walking north and you walk in a straight line for two kilometers. When you look at
the map, you discover that you actually walked one kilometer north and one kilometer
south. How is this possible?
The Cold Drink
At a bar, there is a bucket containing ice, some of which has melted. A bartender gets an
ice cube weighing 20 grams from the ice bucket and puts it into an insulated cup containing
100 grams of water at 20 degrees Celsius. Will the ice cube melt completely? What will be
the final temperature of the water in the cup?
The Philatelist
My sister has six red stamps and three blue ones. In her collection, seven stamps are from
Mexico and six stamps are from France. One stamp is purple and it is not from Mexico or
France. Two of her Mexican stamps are red and one is blue. Two of her French stamps are
blue and three are red. How many stamps does she have?
The Jewelry Box
At an eBay auction, a woman's ring and a filigree jewelry box with a hand-painted ceramic
top are on sale for $200.00 Dollars. The jewelry box is valued at $190.00 Dollars more than
the ring. How much is the ring worth?
The Handshake
At a party, everyone shook hands with everybody else. There were 66 handshakes. How
many people were at the party?
Government Subsidy
The government pays farmers a specific fee for each row of four trees that they plant. An
enterprising, but dishonest farmer found a way of planting five rows of four trees using only
ten trees. How did he do it?
Eye Puzzle
This rectangle of seemingly random colored dots contains a message. Do you know the
answer?
Numerology
Mathematical aptitude tests frequently have sets of numbers where you are supposed to
figure out a pattern or guess the next number. For example,
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(2, 4, 6, 8, 10) is a list of even numbers corresponding to 2×n for n=1, 2, 3, ...
(1, 1, 2, 3, 5) is the well-known Fibonacci series where two adjacent numbers
are added to produce the next number.
(2, 3, 5, 7, 11) is a list of prime numbers.
(1, 2, 4, 8, 16) is an exponential series corresponding to 2n for n=0, 1, 2, ...
Can
you
figure
(2, 6, 10, 15, 19)
out
the
special
significance
of
the
following
sequence?
The Mathematics Class
All students in the physics class also study mathematics. Half of those who study literature
also study mathematics. Half of the students in the mathematics class study physics. Thirty
students study literature and twenty study physics. Nobody who studies literature studies
physics. How many students in the mathematics class study neither physics nor literature?
The Pet Detective
You have been promoted to pet detective while Ace Ventura guides some tourists on a
safari. From the following clues, you must figure out who is the owner of each pet, and
where the pet got lost.
1.
2.
3.
4.
5.
A rabbit and a dog are two of the lost pets.
The pet lost in the garden is owned by Mary.
Robert does not own a dog.
John's pet was lost in the woods.
The cat was not lost in the woods or in the park.
The Wall Street Investor $ $ $
An investor trading through a discount stock broker that charges $10.00 Dollars per
transaction bought 200 shares of Vola Tile Corporation at $50.00 Dollars per share. The
stock quickly increased in value by 50%, but then lost 40% of its value. The investor sold
the stock. How much money did the investor gain or lose?
Boolean Enlightenment
The path to enlightenment lies behind one of two doors. In front of each door stands a
guard who knows which door leads to enlightenment, but one of the guards always lies and
the other one always tells the truth. In your search for enlightenment, you are allowed to
ask one guard only one question that can be answered "yes" or "no", but unfortunately, you
do not know which guard is the liar. You will be banished to the dungeon of logical illiteracy
if you fail in your quest. What question should you ask to find the path to enlightenment?
The Electrician
An electrician has two two-way switches (single-pole, double-throw), a light bulb, and a
power source. How should he connect the terminals so that either switch can be used to
turn the light on or off?
The Hematologist
After many years of looking through a microscope at human blood slides, a hematologist in
a hospital laboratory is very excited that he found five different types of leukocytes (white
blood cells) in a row. The hematologist gives you the following hints so that you can identify
the white cells:
1. The lymphocyte is immediately to the right of the basophil.
2. The neutrophil is immediately to the left of the monocyte.
3. The eosinophil is not adjacent to the monocyte, the neutrophil, or the basophil.
Can you name the white cells from left to right?
Poisons
Hydrochloric acid is a corrosive, fuming, poisonous, highly acidic solution of hydrogen
chloride (HCl). Sodium hydroxide is a caustic, strongly alkaline compound (NaOH) used in
drain cleaners. If ingested, hydrochloric acid corrodes the mucous membranes, esophagus,
and stomach causing dysphagia, nausea, circulatory failure and death. Sodium hydroxide, if
ingested, will cause vomiting, prostration, and collapse. Why is it that if you mix these two
substances in the right proportions before ingesting them you will not have any poisoning
symptoms?
The Thief in the Liars' Club
A valuable painting was stolen from the Liars' Club, but the police are having a hard time
identifying the culprit because every statement made by a member of the Liars' Club is
false. Only four members visited the club on the day that the painting was stolen. This is
what they told the police:
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Ann: None of us took the painting. The painting was here when I left.
Bob: I arrived second. The painting was already gone.
Chuck: I was the third to arrive. The painting was here when I arrived.
Tom: Whoever stole the painting arrived before me. The painting was already
gone.
Who of these four liars stole the painting?
The Botanist
At a farm, you are asked to identify these common plants from their blooms:
The Odd Ball
There are twelve identical-looking balls, but one is either heavier or lighter than the other
eleven. How can you determine which is the odd ball and find out whether this ball is
heavier or lighter than the others using only three weighings with a balance?
The Fruit Vendor
A fruit vendor bought 100 pounds of berries for $2.00 per pound and expected to double his
investment by selling the berries for $4.00 per pound at an open-air market. The vendor
only managed to sell 50 pounds of berries the first day and he sold the remainder on the
second day. The fresh berries had a content of 99% water, but because of the hot weather,
the berries dehydrated and contained only 98% water on the second day. How much profit
did the vendor make?
Three Generations
The grandson is about as many days old as the son is in weeks. The grandson is
approximately as many months old as the father is in years. The ages of the grandson, the
son, and the father add up to 120 years. What are their ages in years?
The Leaning Tower
Built from 1173 to 1350.
Started leaning in 1178.
It is said that Galileo (1564-1642) dropped balls of various weights from the top of the
Leaning Tower of Pisa to refute an Aristotelian belief that heavier objects fall faster than
lighter objects. If the balls were dropped from a height of 54 meters, how long did it take
for the balls to hit the ground?
How fast were the balls going when they hit the ground?
Aquarius
You have to measure exactly 4 liters of water, but you only have a 3-liter bottle and a 5liter bottle. How do you do it?
Ship in a Tub
A toy ship is floating in a cylindrical container 10 centimeters in diameter that is partially
filled with water. How much will the level of the water rise if a silver teddy bear weighing
100 grams is loaded on the ship? By the way, silver has a density of 10.49 g/cc.
If the teddy bear falls off the ship and sinks to the bottom of the container while the ship
continues to float, how much will the level of the water rise compared to the original level
with just the ship?
Canola oil and olive oil mixture
While shopping for groceries, you notice a new cooking oil product consisting of a blend of
canola oil and olive oil. The label does not say in what proportions the oils are mixed, but
the Nutrition Facts panel says that a 14 gram serving has 1 gram of saturated fat, 9 grams
of monounsaturated fat, and 4 grams of polyunsaturated fat. What percentage of olive oil
does the blend contain?