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?
Mrs. Stotch is a fifth grade teacher. One of her students took her apple. Mrs. Stotch has narrowed the suspects down to Billy, Paige, and Tyler. Each of the students give these statements: Billy: I didn’t do it. Paige: I didn’t do it. Tyler: Paige did it! Mrs. Stotch knows that only one of the kids is telling the truth. Who is telling the truth and who took the apple?
A magician was boasting one day at how long he could hold his breath under water. His record was 6 minutes. A kid that was listening said, “That’s nothing, I can stay under water for 10 minutes without using any equipment or air pockets!” The magician told the kid if he could do that, he’d give him $10,000. The kid did it and won the money. Can you figure out how?
You’re in a mansion and the power is out. You see some signs on three doors. One says, “Death from drowning,” another says “Death from machine guns,” and the last one says “Death from electric chair.” Then you see another big sign off to the side that says “Or stay in the mansion and starve to death.” What do you choose and still live?
Anderson, Biggs, and Carpenter were staying together at a place by the seaside. One day they went out in a boat and were a mile at sea when a rifle was fired on shore in their direction. It seems that Anderson only heard the report of the gun, Biggs only saw the smoke, and Carpenter merely saw the bullet strike the water near them. Which of them first knew of the discharge of the rifle?
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?
A man phoned his daughter to ask her to buy a few things he needed for a trip. He told her she would find enough dollar bills for the purchases in an envelope on his desk. She found the envelope with 98 written on it. In a store she bought $90 worth of things, but when it was time to pay she not only didn’t have $8 left over but she was short. By how much was she short of cash, and why?
A boy saw a shirt for $97 but does not have enough cash. So he borrowed $50 from his mom and another $50 from his dad. He bought the shirt, and got back $3 as change. He gave his dad $1 and his mom $1 and kept the other $1 for himself. Now mom and dad paid $10 each and got back $1 each. So they paid $49 each, totaling $98. The boy has another $1, adding up to $99. Where is the missing dollar?
Suppose we lay down two cups in front of you. One of the cups is filled with tea and the other one with coffee. Now we ask you to take a spoonful of tea and mix it with the coffee. At this moment, the coffee cup has a mixture of tea and coffee. You have to take that mixture (spoonful) and add it back to the tea. Can you now tell if the cup of coffee has more tea or the cup of tea has more coffee?
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?
You want to send a valuable object to a friend securely. You have a box that is large enough to contain the object and the box can be fitted with multiple locks. Both of you also have several locks and their corresponding keys. However, your friend does not have the keys to any of your locks. If you send a key in an unlocked box, there is a danger of theft. How can you send the object securely to your friend?
Acting on an anonymous phone call, the police raid a house to arrest a suspected murderer. They don’t know what he looks like but they know his name is John and that he is inside the house. The police bust in on a carpenter, a lorry driver, a mechanic and a fireman playing cards. Without hesitation or communication of any kind, they immediately arrest the fireman. How do they know they’ve got their man?
Acting on an anonymous phone call, the police raid a house to arrest a suspected murderer. They don’t know what he looks like but they know his name is John and that he is inside the house. The police bust in on a carpenter, a lorry driver, a mechanic and a fireman playing cards. Without hesitation or communication of any kind, they immediately arrest the fireman. How do they know they’ve got their man?
A man lives on the twelfth floor of an apartment building. Every morning he takes the elevator down to the lobby and leaves the building. In the evening, he gets into the elevator, and, if there is someone else in the elevator or if it was raining that day, he goes back to his floor directly. Otherwise, he goes to the tenth floor and walks up two flights of stairs to his apartment that is on the twelfth floor. Why?
