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?
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?
At a family reunion were the following people: one grandfather, one grandmother, two fathers, two mothers, four children, three grandchildren, one brother, two sisters, two sons, two daughters, one father-in-law, one mother-in-law, and one daughter-in-law. But not as many people attended as it sounds. How many were there, and who were they?
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?
You have been given the task of transporting 3,000 apples 1,000 miles from Appleland to Bananaville. Your truck can carry 1,000 apples at a time. Every time you travel a mile towards Bananaville you must pay a tax of 1 apple but you pay nothing when going in the other direction (towards Appleland). What is highest number of apples you can get to Bananaville?
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?
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 man forgot the secret code to open his locker. But he remembers the following clues: Fifth number plus the third number equals fourteen. First number is one less than twice the second number. Fourth number is one more than the second number. Second number plus the third number equals ten. Sum of all five numbers is 30. Can you find out the secret code to help him out?
Alice came across a lion and a unicorn in a forest of forgetfulness. Those two are strange beings. The lion lies every Monday, Tuesday and Wednesday and the other days he speaks the truth. The unicorn lies on Thursdays, Fridays and Saturdays, however the other days of the week he speaks the truth. Lion: Yesterday I was lying. Unicorn: So was I. On which day did they say that?
You have two ropes. Each rope can burn in exactly one hour. The ropes are not of the same length or width. Both ropes are also not of uniform width or thickness. The ropes are thick at certain places and thin at other places. Thus, a rope that is half burnt will not necessarily have taken 30 minutes to burn. By burning the ropes, how do you measure exactly 15 minutes worth of time?
In an Island the natives lie and visitors speak truth. A man wants to know whether a salesman beside him in a bar is a native or a visitor. He asked him to ask a woman beside him whether she is a native or visitor. He replied, “She says she is a visitor.” Then he was immediately able to determine if the salesman is a native or a visitor. Is the salesman a native or a visitor?
Abigail, Bridget and Claudia often eat dinner out. Each orders either coffee or tea after dinner. If Abigail orders coffee, then Bridget orders the drink that Claudia orders. If Bridget orders coffee, then Abigail orders the drink that Claudia doesn’t order. If Claudia orders tea, then Abigail orders the drink that Bridget orders. Who always orders the same drink after dinner?
