by Peter Keyne
What can you say to gain your freedom?
2. Barrels of Wine and Beer — A Puzzle by Henry Dudeney
A merchant purchases five barrels of wine and one barrel of beer. The volume (in gallons) of each barrel is shown above. He intends to keep the beer for himself, but is keen to profit on the wine. He is soon able to sell all of it to two customers. One of the customers buys twice as much as the other.
Can you determine which barrel contains the beer?
3. Burning Ropes
You are given two ropes and a lighter, and told that each rope takes exactly one hour to burn. The ropes do not burn at a uniform speed however — some parts of the rope burn more quickly than others.
How is it possible for you to time exactly 45 minutes?
4. An Archaeologist
An archaeologist unearths a coin bearing the inscription “57BC”. How does he instantly know that it’s a forgery?
5. Snail Pace
A snail is at the bottom of a well. Each day it climbs up four feet, but then during the night, it slips down three feet again. If the well is 20-feet deep, how many days will it take the snail to get out?
6. Time Flies
A man is considering how quickly his life has flown by.
He thinks to himself, “the day before yesterday I was 37, and next year I will be 40!”
The man has made no error in his calculation. On what day of the year is his birthday?
7. The Lost Boarding Pass
100 passengers are boarding a plane with 100 seats. The first passenger in line has lost his boarding pass and chooses a random seat to sit in. Each subsequent passenger takes their assigned seat if it is unoccupied. Otherwise, they take a random unoccupied seat.
What is the probability that the last passenger will find their seat unoccupied?
8. Water and Wine
There are two glasses. One contains water, and the other contains an equal quantity of wine.
A teaspoon of water is removed and mixed into the glass of wine. A teaspoon of the wine-water mixture is then removed and mixed into the glass of water.
Which of the mixtures is now purer?
9. Secure Transport
An archaeologist wishes to send a valuable artefact to a museum. However, he has doubts as to the integrity of the couriers, and fears they will keep the artefact for themselves if they get a chance to see it. He has a box, and a selection of locks and their keys, but he knows that the museum curator will not be able to open any of them. If he sends a key along with the box, the courier is sure to look inside.
What plan do he and the curator devise to ensure that the artefact is safely transported?
10. Einstein’s Riddle4
There are five houses on a small road, and each of them is painted a different color. The inhabitants of the houses are all of different nationalities, own different pets, drink different beverages, and play different sports. One of the inhabitants owns a fish.
The challenge is to deduce who it is from the following fifteen statements:
1. The British man lives in a red house.
2. The Swedish man has a dog.
3. The Danish man drinks tea.
4. The green house is to the left of the white house (from the perspective of someone across the street).
5. The owner of the green house drinks coffee.
6. The person who plays polo has a parrot.
7. The owner of the yellow house plays hockey.
8. The owner of the middle house drinks milk.
9. The Norwegian lives in the first house (furthest to the left).
10. The man who plays baseball lives next to the man who has a cat.
11. The man who has a horse lives next to the man who plays hockey.
12. The man who plays tennis drinks orange juice.
13. The German plays golf.
14. The Norwegian lives next to the blue house.
15. The man who plays baseball has a neighbor who drinks water.
Who owns the fish?
Answers: Round 25
1. "You will boil me in a pot."
2. The 20-gallon barrel contains the beer.
The merchant sells x gallons of wine to one customer and 2x gallons of wine to the other. Therefore in total, he sells 3x gallons of wine. This means that the five barrels of wine must add up to a number that is divisible by three.
If there are 15 gallons of beer, there are 104 gallons of wine (16+18+19+20+31). 104 is not evenly divisible by three however, so we will consider the other five possibilities:
16 gallons of beer means 103 gallons of wine.
18 gallons of beer means 101 gallons of wine.
19 gallons of beer means 100 gallons of wine.
20 gallons of beer means 99 gallons of wine.
31 gallons of beer means 88 gallons of wine.
Since 99 gallons is the only quantity of wine evenly divisible by three, the beer must be in the 20-gallon barrel. One customer bought 33 gallons of wine (the 15 and 18-gallon barrels) and the other bought 66 gallons (the 16, 19 and 31-gallon barrels).
3. You should light the first rope at both ends, and the second rope at one end only. The first rope will have burned out completely in 30 minutes (½ the time it takes for the rope to burn out when it is lit at only one end). As things are, the second rope will burn for a further 30 minutes. But as you wish to time just 45 minutes, you should light the other end of the second rope to halve the remaining burn time. When the rope has burned out, 45 minutes will have elapsed in total.
4. The BC/AD dating system could not possibly have been in use before the birth of Christ. The coin must have been minted much later than the inscription suggests.
5. Seventeen days. When the snail reaches the top of the well, it does not slip down again.
6. His birthday is on December 31st, and he is thinking about it on January 1st. The day before his birthday, he was 37. He then turned 38 on December 31st, and the new year began the following day. Therefore, he will turn 39 this year, and 40 the following year.
7. 50%.
When the last passenger boards the plane, there are only two possibilities:
1) The remaining seat is their assigned seat.
2) The remaining seat is the first passenger’s assigned seat.
The boarding passengers do not show any preference for either of these seats, and therefore they are equally as likely to be the last remaining seat.
8. The mixtures are of equal purity.
We know that there is an equal quantity of liquid in each glass. If we imagine that it is 100ml, it means that there is always 100ml of water and 100ml of wine divided between the two glasses. If x amount of water is in one glass; x amount of wine must be in the other. This remains the case regardless of how many times we transfer water and wine between the two glasses.
Examples:
If one glass contains a mixture of, 82ml of water and 18ml of wine, it means that the other glass must contain a mixture of 18ml of water and 82ml of wine, and that the mixtures are equally pure.
If one glass contains a mixture of 99ml of water and 1ml of wine, it means that the other glass must contain a mixture of 1ml of water and 99ml of wine, and that the mixtures are equally pure.
9. The archaeologist places the artefact inside the box and secures it with one of his locks. He sends it via courier to the museum curator, who attaches his own lock to the box and returns it. The archaeologist then removes his lock and sends it back. The curator can now remove his own lock and access the artefact.
10. The German owns the fish.
The most effective approach for solving this puzzle is to create a table and take note of the facts as you deduce them.
Organization of Table
Complete Table and Solution
*Illustrations
Thank You for Reading
So, you’ve made it through 250 puzzles! We hope you’ve enjoyed them. If you have, please leave us a review with Amazon.
We ca
n be contacted at [email protected], and would love to hear your thoughts about this book and others in the Elsinore Books collection.
Thank you,
Peter Keyne and Rudolph Amsel
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The beauty in these fragments is best unlocked by reading them aloud, savouring the rhythms, the rich ambiguity of metaphor, and vivid evocation of scene. Learn them by heart if you can, and when inspired, revisit the complete plays and admire the passages anew in their native soil.
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Illustrations
* The authors of this book would like to express their gratitude to Freepik.com for their design work, which has furnished this book with its illustrations and cover page.
Images "Designed by Freepik.com" and modified for the purposes of this book. Licensed CC BY 3.0.
Notes
[←1]
Several answers are possible if you think creatively. Can you come up with two?
[←2]
This Riddle comes from Alice’s Adventures in Wonderland. In the chapter "A Mad Tea Party", the Hatter asks Alice “Why is a raven like a writing desk?" When Alice gives up, the Hatter admits that he doesn’t have the slightest idea either.
[←3]
It comes from A Little Book of Language by the linguist, David Crystal.
[←4]
This puzzle is frequently attributed to Albert Einstein, and accompanied by a claim that only 2% of the population are intelligent enough to solve it. There is no evidence to support the attribution or the claim.
Table of Contents
A Short Introduction
Table of Contents
Round 1: Old Chestnuts Warmed Up
Round 2: Pure Logic 1
Round 3: Coins, Cups and Toothpicks
Round 4: Words Words Words 1
Round 5: A Different Way of Seeing
Round 6: The Tale’s the Thing: Lateral Thinking Puzzles 1
Round 7: What am I? Painting Word Pictures
Round 8: Number Puzzlers
Round 9: Brainbats
Round 10: Pure Logic 2
Round 11: Listen Carefully
Round 12: Words Words Words 2
Round 13: Pen and Paper
Round 14: What am I? New Riddles
Round 15: Ditloids
Round 16: Number Puzzlers 2
Round 17: Pure Logic 3
Round 18: Plain Ridiculous!
Round 19: The Great Riddles from Literature
Round 20: Outside the Box
Round 21: The Tale’s the Thing: Lateral Thinking Puzzles 2
Round 22: Contradictories
Round 23: Coins, Cups and Toothpicks 2
Round 24: Words, Words, Words 3
Round 25: Pure Logic 4
Thank You for Reading
Other Titles by Elsinore Books
Illustrations
