There are 10 identical bags of coins. Each bag contains 100 coins. In one bag the coins are silver, in the others gold. All the coins are identical. A gold coin weigh 10 grams and a silver coin weigh a gram less. Given a regular measurement scale, how would you determine in one weighing which bag does not have the gold coins?
A king is on a cross-sea voyage and as soon as he gets off of the ship he spots an elephant. He decides to take it home, but first, he wants to know its weight. The largest scale they brought only weighs up to 50 pounds. He asks his smartest scholar to come up with a solution. How does the scholar find the weight of the elephant?
If the puzzle you solved before you solved the puzzle you solved after you solved the puzzle you solved before you solved this one, was harder than the puzzle you solved after you solved the puzzle you solved before you solved this one, was the puzzle you solved before you solved this one harder than this one? The answer is yes or no?
You need to check that your friend, Bob, has your correct phone number, but you cannot ask him directly. You must write the question on a card and give it to Eve who will take the card to Bob and return the answer to you. What must you write on the card, to ensure Bob can encode the message so that Eve cannot read your phone number?
In a class, the number of girls who do wear a watch is double the number who don’t. But the number of boys who do not wear a watch is double the number who do. If I tell you the number of girls in my class is double the number of boys, Can you tell me the number of students I teach? Here’s a clue: More than 20; below 32.
Three professors were discussing over how long they have been teaching. Andrew and Beyonce have been teaching for a total of thirty six years. Curt and Beyonce have been teaching for a total of twenty two years. Curt and Andrew have been teaching for a total of twenty eight years. Can you find out how long have each of them been teaching?
I live on Sunset Boulevard, where there are 6 houses on my side of the block. The house numbers are consecutive even numbers. The sum of all 6 house numbers is 8790. You don’t know which block I live on, and it’s a long street, but I will tell you that I live in the lowest number on my side of the block. What’s my address?
A hunter met two shepherds, one of whom had three loaves of bread and the other, five loaves. All the loaves were the same size. The three men agreed to share the eight loaves equally between them. After they had eaten, the hunter gave the shepherds eight bronze coins as payment for his meal. How should the two shepherds fairly divide this money?
There are 21 barrels of wine with a farmer. 7 are full, 7 are half full and 7 are empty. He wishes to divide them among his three sons such that each son has the same number of full barrels, the same number of half full barrels, and the same number of empty barrels. Note that there are no measuring devices handy. How can the barrels and wine be evenly divided?
A man is trapped in a room with 2 doors and a small hole in the ceiling 10 inches in diameter. Behind one of the doors is an extremely hungry lion that hasn’t eaten in a couple of days. Behind the other door is a glass tunnel that magnifies the heat from the sun creating temperatures so high that even opening the door could kill you. How does the man escape?
James ordered a fishing rod. Unfortunately, James is an Eskimo who lives in a very remote part of Greenland and the import rules there forbid any package longer than 4 feet to be imported. The fishing rod is 4 feet and 1 inch, just a little too long, so how can the fishing rod be mailed to James without breaking the rules? The fishing rod has to arrive in one piece.
Jolene, Charlie and Natalie were classmates. One of them cleaned up the classroom one day while there was nobody around. Below are their replies when the teacher questioned about who cleaned up the classroom. Jolene: Charlie cleaned the classroom. Charlie: I did not do it! Natalie: Neither did I! If one of them was telling the truth, who cleaned up the classroom?
During a school lunch break, ten kids are discussing about their holiday jobs. In particular, they would like to know their average monthly salary (for the ten of them), but no one wants to admit openly exactly how much they make. Can you devise a way for them to calculate their average (mean) salary without anyone having to tell anyone else what their individual salaries are?
A rich and handsome man named James Leonard was murdered on a Sunday afternoon. At the time of the murder there was: the maid, the cook, the butler, the gardener and the wife. Maid: I was fixing the table. Cook: I was cooking breakfast. Butler: I was polishing the silverware and the dishes. Gardener: I was planting tomato seeds. Wife: I was reading a book. Who did it?
A man wants to enter an exclusive club, but he doesn’t know the password. Another man walks to the door and the doorman says 12, the man says 6, and is let in. Another man walks up and the doorman says 6, the man says 3, and is let in. Thinking he had heard enough, he walks up to the door and the doorman says 10, he says 5, and he isn’t let in. What should he have said?
